Problem #145

You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

func prodSigns(arr: [Int]) -> Int? { ...

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9)
XCTAssertTrue(prodSigns(arr: [0, 1]) == 0)
XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10)
XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil)
XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20)
XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4)
XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4)
XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0)

0.65 Compiled
0.32 Passed

Problem #145 Experiment #27

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    for i in 0..<arr.count {
        result += arr[i] * arr.reduce(1, { $0 * $1 })
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    for i in 0..<arr.count {
        result += arr[i] * arr.reduce(1, { $0 * $1 })
    }
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    var product = 1
    for i in arr {
        product *= i
    }
    for i in arr {
        if i == 0 {
            result += 0
        } else {
            result += i * product
        }
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    var product = 1
    for i in arr {
        product *= i
    }
    for i in arr {
        if i == 0 {
            result += 0
        } else {
            result += i * product
        }
    }
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for i in 0..<arr.count {
        product *= arr[i]
    }
    
    for i in 0..<arr.count {
        if arr[i] == 0 {
            continue
        }
        
        if arr[i] < 0 {
            sum += product / abs(arr[i])
        } else {
            sum += product * arr[i]
        }
    }
    
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for i in 0..<arr.count {
        product *= arr[i]
    }
    
    for i in 0..<arr.count {
        if arr[i] == 0 {
            continue
        }
        
        if arr[i] < 0 {
            sum += product / abs(arr[i])
        } else {
            sum += product * arr[i]
        }
    }
    
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for i in arr {
        product *= i
    }
    
    for i in arr {
        if i == 0 {
            continue
        }
        
        if i > 0 {
            sum += product / i
        } else {
            sum -= product / i
        }
    }
    
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for i in arr {
        product *= i
    }
    
    for i in arr {
        if i == 0 {
            continue
        }
        
        if i > 0 {
            sum += product / i
        } else {
            sum -= product / i
        }
    }
    
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    var result = 0
    for i in 0..<arr.count {
        result += arr[i] * arr.reduce(1, { $0 * $1 })
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    var result = 0
    for i in 0..<arr.count {
        result += arr[i] * arr.reduce(1, { $0 * $1 })
    }
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // your code here
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // your code here
}
<|file_separator|>

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
    // your code
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // your code
}
<|file_separator|>

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var product = 1
    for i in arr {
        product *= i
    }
    
    for i in arr {
        if i == 0 {
            result = 0
        } else {
            result += i * product
        }
    }
    
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var product = 1
    for i in arr {
        product *= i
    }
    
    for i in arr {
        if i == 0 {
            result = 0
        } else {
            result += i * product
        }
    }
    
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    for i in 0..<arr.count {
        result += arr[i] * arr.reduce(1, { $0 * $1 })
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    for i in 0..<arr.count {
        result += arr[i] * arr.reduce(1, { $0 * $1 })
    }
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    var result = 0
    for i in 0..<arr.count {
        result += arr[i] * (arr[i] > 0 ? 1 : -1)
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    var result = 0
    for i in 0..<arr.count {
        result += arr[i] * (arr[i] > 0 ? 1 : -1)
    }
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

Problem #145 Experiment #28

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        product *= num > 0 ? 1 : -1
        sum += abs(num)
    }
    return product * sum
}

<bos><start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        product *= num > 0 ? 1 : -1
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : num > 0 ? 1 : -1
        sum += abs(num)
    }
    return product * sum
}

<bos><start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : num > 0 ? 1 : -1
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            sum = 0
            product = 1
        } else {
            sum += abs(num)
            product *= (num > 0) ? 1 : -1
        }
    }
    return product * sum
}

<bos><start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            sum = 0
            product = 1
        } else {
            sum += abs(num)
            product *= (num > 0) ? 1 : -1
        }
    }
    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : num > 0 ? 1 : -1
        sum += abs(num)
    }
    return product * sum
}

<bos><start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : num > 0 ? 1 : -1
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : num > 0 ? 1 : -1
        sum += abs(num)
    }
    return product * sum
}

<bos><start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : num > 0 ? 1 : -1
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num > 0 ? 1 : (num < 0 ? -1 : 0)
        sum += abs(num)
    }
    return product * sum
}

<bos><start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num > 0 ? 1 : (num < 0 ? -1 : 0)
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return product * sum
}

<bos><start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= (num == 0) ? 1 : num / abs(num)
        sum += abs(num)
    }
    return product * sum
}

<bos><start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= (num == 0) ? 1 : num / abs(num)
        sum += abs(num)
    }
    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return product * sum
}

<bos><start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        product *= num > 0 ? 1 : -1
        sum += abs(num)
    }
    return product * sum
}

<bos><start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        product *= num > 0 ? 1 : -1
        sum += abs(num)
    }
    return product * sum
}
```

Problem #145 Experiment #29

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= num < 0? -1 : 1 // integer literal is unused

result *= num < 0? -1 : 1 // expected expression

result *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    return arr.reduce(1, { $0 * $1.sign })
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    return arr.reduce(1, { $0 * $1.sign })
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

return arr.reduce(1, { $0 * $1.sign }) // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    return arr.reduce(1, { $0 * $1.sign })
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    return arr.reduce(1, { $0 * $1.sign })
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

return arr.reduce(1, { $0 * $1.sign }) // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    return arr.reduce(1, { $0 * $1.sign })
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    return arr.reduce(1, { $0 * $1.sign })
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

return arr.reduce(1, { $0 * $1.sign }) // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= num < 0? -1 : 1 // integer literal is unused

result *= num < 0? -1 : 1 // expected expression

result *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for i in arr {
        result *= i < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for i in arr {
        result *= i < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= i < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= i < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= i < 0? -1 : 1 // integer literal is unused

result *= i < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= i < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= i < 0? -1 : 1 // expected expression

result *= i < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num.sign
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num.sign
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for i in arr {
        result *= i < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for i in arr {
        result *= i < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= i < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= i < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= i < 0? -1 : 1 // integer literal is unused

result *= i < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= i < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= i < 0? -1 : 1 // expected expression

result *= i < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var result = 1
    for i in 0..<arr.count {
        result *= arr[i] * sign(arr[i])
    }
    return result
}

func sign(_ n: Int) -> Int {
    return n < 0? -1 : 1
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var result = 1
    for i in 0..<arr.count {
        result *= arr[i] * sign(arr[i])
    }
    return result
}

func sign(_ n: Int) -> Int {
    return n < 0? -1 : 1
}
```

return n < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

return n < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

return n < 0? -1 : 1 // integer literal is unused

return n < 0? -1 : 1 // cannot convert return expression of type 'Bool' to return type 'Int'

return n < 0? -1 : 1 // expected expression

return n < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

return n < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var product = 1
    var positive = 0
    var negative = 0
    for num in arr {
        if num == 0 {
            product *= 0
        } else if num > 0 {
            positive += 1
        } else {
            negative += 1
        }
    }
    return product * positive * negative
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var product = 1
    var positive = 0
    var negative = 0
    for num in arr {
        if num == 0 {
            product *= 0
        } else if num > 0 {
            positive += 1
        } else {
            negative += 1
        }
    }
    return product * positive * negative
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #30

func prodSigns(arr: [Int]) -> Int? {
  guard!arr.isEmpty else { return nil }
  let prod = arr.reduce(1, *)
  let signs = arr.map { $0 > 0? 1 : -1 }
  let sum = signs.reduce(0, +)
  return prod * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
  guard!arr.isEmpty else { return nil }
  let prod = arr.reduce(1, *)
  let signs = arr.map { $0 > 0? 1 : -1 }
  let sum = signs.reduce(0, +)
  return prod * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 > 0? 1 : -1 } // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let signs = arr.map { $0 > 0? 1 : -1 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 > 0? 1 : -1 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 > 0? 1 : -1 } // cannot use optional chaining on non-optional value of type 'Int'

let signs = arr.map { $0 > 0? 1 : -1 } // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        result *= sign
        sign = i > 0? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        result *= sign
        sign = i > 0? 1 : -1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

sign = i > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

sign = i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

sign = i > 0? 1 : -1 // integer literal is unused

sign = i > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

sign = i > 0? 1 : -1 // expected expression

sign = i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

sign = i > 0? 1 : -1 // cannot assign value of type 'Bool' to type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num < 0? -1 : 1
        sum += abs(num)
    }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num < 0? -1 : 1
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            sign = 0
        } else {
            result *= sign
            sign = i > 0? 1 : -1
        }
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            sign = 0
        } else {
            result *= sign
            sign = i > 0? 1 : -1
        }
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

sign = i > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

sign = i > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

sign = i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

sign = i > 0? 1 : -1 // expected expression

sign = i > 0? 1 : -1 // cannot assign value of type 'Bool' to type 'Int'

sign = i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

sign = i > 0? 1 : -1 // integer literal is unused

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var product = 1
    var sum = 0
    for i in arr {
        product *= i > 0? 1 : -1
        sum += abs(i)
    }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var product = 1
    var sum = 0
    for i in arr {
        product *= i > 0? 1 : -1
        sum += abs(i)
    }
    return product * sum
}
```

product *= i > 0? 1 : -1 // expected expression

product *= i > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= i > 0? 1 : -1 // integer literal is unused

product *= i > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= i > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

product *= i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
        } else {
            product *= num < 0? -1 : 1
        }
        sum += abs(num)
    }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
        } else {
            product *= num < 0? -1 : 1
        }
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            result = 0
            break
        }
        if i < 0 {
            sign *= -1
        }
        result *= i
    }
    return result * sign
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            result = 0
            break
        }
        if i < 0 {
            sign *= -1
        }
        result *= i
    }
    return result * sign
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        result *= sign
        sign *= i > 0? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        result *= sign
        sign *= i > 0? 1 : -1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

sign *= i > 0? 1 : -1 // integer literal is unused

sign *= i > 0? 1 : -1 // expected expression

sign *= i > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

sign *= i > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

sign *= i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

sign *= i > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

sign *= i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            result = 0
            break
        }
        result *= sign
        sign = i > 0? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            result = 0
            break
        }
        result *= sign
        sign = i > 0? 1 : -1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

sign = i > 0? 1 : -1 // cannot assign value of type 'Bool' to type 'Int'

sign = i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

sign = i > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

sign = i > 0? 1 : -1 // integer literal is unused

sign = i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

sign = i > 0? 1 : -1 // expected expression

sign = i > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for i in arr {
        product *= i < 0? -1 : 1
        sum += abs(i)
    }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for i in arr {
        product *= i < 0? -1 : 1
        sum += abs(i)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= i < 0? -1 : 1 // expected expression

product *= i < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= i < 0? -1 : 1 // integer literal is unused

product *= i < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= i < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= i < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= i < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

Problem #145 Experiment #31

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    return arr.reduce(1) { $0 * sign($1) } * magnitudes(arr).reduce(1, *)
}

func sign(_ n: Int) -> Int {
    return n == 0? 0 : n / abs(n)
}

func magnitudes(_ arr: [Int]) -> [Int] {
    return arr.map { abs($0) }
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    return arr.reduce(1) { $0 * sign($1) } * magnitudes(arr).reduce(1, *)
}

func sign(_ n: Int) -> Int {
    return n == 0? 0 : n / abs(n)
}

func magnitudes(_ arr: [Int]) -> [Int] {
    return arr.map { abs($0) }
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

return n == 0? 0 : n / abs(n) // expected expression

return n == 0? 0 : n / abs(n) // integer literal is unused

return n == 0? 0 : n / abs(n) // cannot convert return expression of type 'Bool' to return type 'Int'

return n == 0? 0 : n / abs(n) // consecutive statements on a line must be separated by ';'

return n == 0? 0 : n / abs(n) // cannot use optional chaining on non-optional value of type 'Int'

return n == 0? 0 : n / abs(n) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    return arr.isEmpty? nil : arr.reduce(1) { $0 * ($1 == 0? 0 : $1 / abs($1)) }
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    return arr.isEmpty? nil : arr.reduce(1) { $0 * ($1 == 0? 0 : $1 / abs($1)) }
}
```

return arr.isEmpty? nil : arr.reduce(1) { $0 * ($1 == 0? 0 : $1 / abs($1)) } // type of expression is ambiguous without a type annotation

return arr.isEmpty? nil : arr.reduce(1) { $0 * ($1 == 0? 0 : $1 / abs($1)) } // 'nil' requires a contextual type

return arr.isEmpty? nil : arr.reduce(1) { $0 * ($1 == 0? 0 : $1 / abs($1)) } // consecutive statements on a line must be separated by ';'

return arr.isEmpty? nil : arr.reduce(1) { $0 * ($1 == 0? 0 : $1 / abs($1)) } // consecutive statements on a line must be separated by ';'

return arr.isEmpty? nil : arr.reduce(1) { $0 * ($1 == 0? 0 : $1 / abs($1)) } // expected expression

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            return 0
        }
        prod *= i < 0? -1 : 1
        sum += abs(i)
    }
    return sum * prod
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            return 0
        }
        prod *= i < 0? -1 : 1
        sum += abs(i)
    }
    return sum * prod
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

prod *= i < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

prod *= i < 0? -1 : 1 // expected expression

prod *= i < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

prod *= i < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

prod *= i < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

prod *= i < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

prod *= i < 0? -1 : 1 // integer literal is unused

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        product *= num < 0? -1 : 1
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        product *= num < 0? -1 : 1
        sum += abs(num)
    }
    return sum * product
}
```

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        product *= num > 0? 1 : -1
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        product *= num > 0? 1 : -1
        sum += abs(num)
    }
    return sum * product
}
```

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // integer literal is unused

product *= num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : -1 // expected expression

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty {
    return nil
  }
  var product = 1
  var sum = 0
  for i in arr {
    if i == 0 {
      product = 0
      break
    }
    product *= i > 0? 1 : -1
    sum += abs(i)
  }
  return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty {
    return nil
  }
  var product = 1
  var sum = 0
  for i in arr {
    if i == 0 {
      product = 0
      break
    }
    product *= i > 0? 1 : -1
    sum += abs(i)
  }
  return product * sum
}
```

product *= i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= i > 0? 1 : -1 // integer literal is unused

product *= i > 0? 1 : -1 // expected expression

product *= i > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= i > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= i > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sign = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            sign = 0
            break
        } else if num < 0 {
            sign *= -1
        }
        sum += abs(num)
    }
    return sum * sign
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sign = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            sign = 0
            break
        } else if num < 0 {
            sign *= -1
        }
        sum += abs(num)
    }
    return sum * sign
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var zeros = 0
    for num in arr {
        if num == 0 {
            zeros += 1
            continue
        }
        product *= num < 0? -1 : 1
    }
    return zeros > 0? 0 : product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var zeros = 0
    for num in arr {
        if num == 0 {
            zeros += 1
            continue
        }
        product *= num < 0? -1 : 1
    }
    return zeros > 0? 0 : product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

return zeros > 0? 0 : product // cannot convert return expression of type 'Bool' to return type 'Int?'

return zeros > 0? 0 : product // cannot use optional chaining on non-optional value of type 'Int'

return zeros > 0? 0 : product // consecutive statements on a line must be separated by ';'

return zeros > 0? 0 : product // integer literal is unused

return zeros > 0? 0 : product // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

return zeros > 0? 0 : product // expected expression

return zeros > 0? 0 : product // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    // your code here
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // your code here
}
```

} // missing return in global function expected to return 'Int?'

Problem #145 Experiment #32

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    let positiveCount = arr.filter({ $0 > 0 }).count
    let negativeCount = arr.filter({ $0 < 0 }).count
    let zeroCount = arr.filter({ $0 == 0 }).count
    let totalMagnitude = arr.reduce(0, { $0 + abs($1) })
    let totalSign = positiveCount % 2 == 0? 1 : -1
    return totalMagnitude * totalSign
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    let positiveCount = arr.filter({ $0 > 0 }).count
    let negativeCount = arr.filter({ $0 < 0 }).count
    let zeroCount = arr.filter({ $0 == 0 }).count
    let totalMagnitude = arr.reduce(0, { $0 + abs($1) })
    let totalSign = positiveCount % 2 == 0? 1 : -1
    return totalMagnitude * totalSign
}
```

let totalSign = positiveCount % 2 == 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

let totalSign = positiveCount % 2 == 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let totalSign = positiveCount % 2 == 0? 1 : -1 // expected expression

let totalSign = positiveCount % 2 == 0? 1 : -1 // integer literal is unused

let totalSign = positiveCount % 2 == 0? 1 : -1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var sign = 1
    for num in arr {
        sum += abs(num)
        sign *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * sign
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var sign = 1
    for num in arr {
        sum += abs(num)
        sign *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * sign
}
```

sign *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

sign *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

sign *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

sign *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

sign *= num > 0? 1 : num < 0? -1 : 0 // expected expression

sign *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

sign *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    return positiveCount * negativeCount * zeroCount
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    return positiveCount * negativeCount * zeroCount
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    return positiveCount * negativeCount * zeroCount
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    return positiveCount * negativeCount * zeroCount
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    return positiveCount * negativeCount * zeroCount
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    return positiveCount * negativeCount * zeroCount
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    let positiveCount = arr.filter({ $0 > 0 }).count
    let negativeCount = arr.filter({ $0 < 0 }).count
    let zeroCount = arr.filter({ $0 == 0 }).count
    return positiveCount * negativeCount * zeroCount
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    let positiveCount = arr.filter({ $0 > 0 }).count
    let negativeCount = arr.filter({ $0 < 0 }).count
    let zeroCount = arr.filter({ $0 == 0 }).count
    return positiveCount * negativeCount * zeroCount
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    var sum = 0
    var sign = 1
    for num in arr {
        sum += abs(num)
        sign *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * sign
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    var sum = 0
    var sign = 1
    for num in arr {
        sum += abs(num)
        sign *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * sign
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

sign *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

sign *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

sign *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

sign *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

sign *= num > 0? 1 : num < 0? -1 : 0 // expected expression

sign *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

sign *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    return positiveCount * negativeCount * zeroCount
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    return positiveCount * negativeCount * zeroCount
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    
    return positiveCount * negativeCount * arr.reduce(0, { $0 + abs($1) })
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    
    return positiveCount * negativeCount * arr.reduce(0, { $0 + abs($1) })
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    let totalCount = positiveCount + negativeCount + zeroCount
    let totalSum = arr.reduce(0, +)
    let totalProduct = positiveCount % 2 == 0? 1 : -1
    return totalSum * totalProduct
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    let totalCount = positiveCount + negativeCount + zeroCount
    let totalSum = arr.reduce(0, +)
    let totalProduct = positiveCount % 2 == 0? 1 : -1
    return totalSum * totalProduct
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

let totalProduct = positiveCount % 2 == 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let totalProduct = positiveCount % 2 == 0? 1 : -1 // integer literal is unused

let totalProduct = positiveCount % 2 == 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let totalProduct = positiveCount % 2 == 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

let totalProduct = positiveCount % 2 == 0? 1 : -1 // expected expression

Problem #145 Experiment #38

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num < 0? -1 : 1
            sum += abs(num)
        }
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num < 0? -1 : 1
            sum += abs(num)
        }
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num < 0? -1 : 1
            sum += abs(num)
        }
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num < 0? -1 : 1
            sum += abs(num)
        }
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num > 0? 1 : -1
            sum += abs(num)
        }
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num > 0? 1 : -1
            sum += abs(num)
        }
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // integer literal is unused

product *= num > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // expected expression

product *= num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num < 0? -1 : 1
            sum += abs(num)
        }
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num < 0? -1 : 1
            sum += abs(num)
        }
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num < 0? -1 : 1
            sum += abs(num)
        }
    }

    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num < 0? -1 : 1
            sum += abs(num)
        }
    }

    return product * sum
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        }
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        }
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            sum += num.magnitude
            product *= num < 0? -1 : 1
        }
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            sum += num.magnitude
            product *= num < 0? -1 : 1
        }
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

sum += num.magnitude // cannot convert value of type 'UInt' to expected argument type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += num.magnitude
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += num.magnitude
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

sum += num.magnitude // cannot convert value of type 'UInt' to expected argument type 'Int'

Problem #145 Experiment #39

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }

    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }

    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }

    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }

    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num > 0? 1 : num < 0? -1 : 0
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num > 0? 1 : num < 0? -1 : 0
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num > 0? 1 : num < 0? -1 : 0 // expected expression

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

Problem #145 Experiment #40

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        switch num {
        case 0:
            product = 0
            break
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default: break
        }
        sum += abs(num)
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        switch num {
        case 0:
            product = 0
            break
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default: break
        }
        sum += abs(num)
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let product = magnitudes.reduce(1, *)
    let sum = signs.reduce(0, +)
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let product = magnitudes.reduce(1, *)
    let sum = signs.reduce(0, +)
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // expected expression

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let product = magnitudes.reduce(1, *)
    let sum = magnitudes.reduce(0, +)
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let product = magnitudes.reduce(1, *)
    let sum = magnitudes.reduce(0, +)
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // expected expression

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let product = magnitudes.reduce(1, *)
    return product * signs.reduce(1, *)
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let product = magnitudes.reduce(1, *)
    return product * signs.reduce(1, *)
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // expected expression

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let product = magnitudes.reduce(1, *)
    let sum = signs.reduce(0, +)
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let product = magnitudes.reduce(1, *)
    let sum = signs.reduce(0, +)
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // expected expression

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 > 0? 1 : -1 } // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= 1
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

Problem #145 Experiment #41

import Foundation

func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

```swift
import Foundation

/* 
 Function to multiply two matrices represented as 2D arrays of Doubles.
 Returns a new matrix that is the product of `lhs` and `rhs`, or `nil` if the matrices cannot be multiplied.
 */
func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

/*
 You are given an array arr of integers and you need to return
 sum of magnitudes of integers multiplied by product of all signs
 of each number in the array, represented by 1, -1 or 0.
 Note: return nil for empty arr.
 Example:
 prodSigns(arr: [1, 2, 2, -4]) == 9
 prodSigns(arr: [0, 1]) == 0
 prodSigns(arr: [] as [Int]) == nil
 */
func prodSigns(arr: [Int]) -> Int? {

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

import Foundation

func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

```swift
import Foundation

/* 
 Function to multiply two matrices represented as 2D arrays of Doubles.
 Returns a new matrix that is the product of `lhs` and `rhs`, or `nil` if the matrices cannot be multiplied.
 */
func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

/*
 You are given an array arr of integers and you need to return
 sum of magnitudes of integers multiplied by product of all signs
 of each number in the array, represented by 1, -1 or 0.
 Note: return nil for empty arr.
 Example:
 prodSigns(arr: [1, 2, 2, -4]) == 9
 prodSigns(arr: [0, 1]) == 0
 prodSigns(arr: [] as [Int]) == nil
 */
func prodSigns(arr: [Int]) -> Int? {
    
    
    
    
    var result = 0
    for

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

import Foundation

func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

```swift
import Foundation

/* 
 Function to multiply two matrices represented as 2D arrays of Doubles.
 Returns a new matrix that is the product of `lhs` and `rhs`, or `nil` if the matrices cannot be multiplied.
 */
func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

/*
 You are given an array arr of integers and you need to return
 sum of magnitudes of integers multiplied by product of all signs
 of each number in the array, represented by 1, -1 or 0.
 Note: return nil for empty arr.
 Example:
 prodSigns(arr: [1, 2, 2, -4]) == 9
 prodSigns(arr: [0, 1]) == 0
 prodSigns(arr: [] as [Int]) == nil
 */
func prodSigns(arr: [Int]) -> Int? {

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

import Foundation

func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

```swift
import Foundation

/* 
 Function to multiply two matrices represented as 2D arrays of Doubles.
 Returns a new matrix that is the product of `lhs` and `rhs`, or `nil` if the matrices cannot be multiplied.
 */
func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

/*
 You are given an array arr of integers and you need to return
 sum of magnitudes of integers multiplied by product of all signs
 of each number in the array, represented by 1, -1 or 0.
 Note: return nil for empty arr.
 Example:
 prodSigns(arr: [1, 2, 2, -4]) == 9
 prodSigns(arr: [0, 1]) == 0
 prodSigns(arr: [] as [Int]) == nil
 */
func prodSigns(arr: [Int]) -> Int? {

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

import Foundation

func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

```swift
import Foundation

/* 
 Function to multiply two matrices represented as 2D arrays of Doubles.
 Returns a new matrix that is the product of `lhs` and `rhs`, or `nil` if the matrices cannot be multiplied.
 */
func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

/*
 You are given an array arr of integers and you need to return
 sum of magnitudes of integers multiplied by product of all signs
 of each number in the array, represented by 1, -1 or 0.
 Note: return nil for empty arr.
 Example:
 prodSigns(arr: [1, 2, 2, -4]) == 9
 prodSigns(arr: [0, 1]) == 0
 prodSigns(arr: [] as [Int]) == nil
 */
func prodSigns(arr: [Int]) -> Int? {

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

import Foundation

func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

```swift
import Foundation

/* 
 Function to multiply two matrices represented as 2D arrays of Doubles.
 Returns a new matrix that is the product of `lhs` and `rhs`, or `nil` if the matrices cannot be multiplied.
 */
func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

/*
 You are given an array arr of integers and you need to return
 sum of magnitudes of integers multiplied by product of all signs
 of each number in the array, represented by 1, -1 or 0.
 Note: return nil for empty arr.
 Example:
 prodSigns(arr: [1, 2, 2, -4]) == 9
 prodSigns(arr: [0, 1]) == 0
 prodSigns(arr: [] as [Int]) == nil
 */
func prodSigns(arr: [Int]) -> Int? {
    
    
    
    var result = 0
    for i in
    
    = 0
    0
    for
    =

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

import Foundation

func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

```swift
import Foundation

/* 
 Function to multiply two matrices represented as 2D arrays of Doubles.
 Returns a new matrix that is the product of `lhs` and `rhs`, or `nil` if the matrices cannot be multiplied.
 */
func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

/*
 You are given an array arr of integers and you need to return
 sum of magnitudes of integers multiplied by product of all signs
 of each number in the array, represented by 1, -1 or 0.
 Note: return nil for empty arr.
 Example:
 prodSigns(arr: [1, 2, 2, -4]) == 9
 prodSigns(arr: [0, 1]) == 0
 prodSigns(arr: [] as [Int]) == nil
 */
func prodSigns(arr: [Int]) -> Int? {
    
    
    
    
    
    var result = [[Double]
    for

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

import Foundation

func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

```swift
import Foundation

/* 
 Function to multiply two matrices represented as 2D arrays of Doubles.
 Returns a new matrix that is the product of `lhs` and `rhs`, or `nil` if the matrices cannot be multiplied.
 */
func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

/*
 You are given an array arr of integers and you need to return
 sum of magnitudes of integers multiplied by product of all signs
 of each number in the array, represented by 1, -1 or 0.
 Note: return nil for empty arr.
 Example:
 prodSigns(arr: [1, 2, 2, -4]) == 9
 prodSigns(arr: [0, 1]) == 0
 prodSigns(arr: [] as [Int]) == nil
 */
func prodSigns(arr: [Int]) -> Int? {

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

import Foundation

func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

```swift
import Foundation

/* 
 Function to multiply two matrices represented as 2D arrays of Doubles.
 Returns a new matrix that is the product of `lhs` and `rhs`, or `nil` if the matrices cannot be multiplied.
 */
func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

/*
 You are given an array arr of integers and you need to return
 sum of magnitudes of integers multiplied by product of all signs
 of each number in the array, represented by 1, -1 or 0.
 Note: return nil for empty arr.
 Example:
 prodSigns(arr: [1, 2, 2, -4]) == 9
 prodSigns(arr: [0, 1]) == 0
 prodSigns(arr: [] as [Int]) == nil
 */
func prodSigns(arr: [Int]) -> Int? {
    
    
    
    
    var result = [[Double]()
    for i in

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

import Foundation

func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

```swift
import Foundation

/* 
 Function to multiply two matrices represented as 2D arrays of Doubles.
 Returns a new matrix that is the product of `lhs` and `rhs`, or `nil` if the matrices cannot be multiplied.
 */
func multiply(_ lhs: [[Double]], _ rhs: [[Double]]) -> [[Double]]? {
    guard lhs[0].count == rhs.count else { 
        return nil 
    }
    
    var result = [[Double]](repeating: [Double](repeating: 0, count: rhs[0].count), count: lhs.count)
    for i in 0..<lhs.count {
        for j in 0..<rhs[0].count {
            for k in 0..<rhs.count {
                result[i][j] += lhs[i][k] * rhs[k][j]
            }
        }
    }
    
    return result
}

/*
 You are given an array arr of integers and you need to return
 sum of magnitudes of integers multiplied by product of all signs
 of each number in the array, represented by 1, -1 or 0.
 Note: return nil for empty arr.
 Example:
 prodSigns(arr: [1, 2, 2, -4]) == 9
 prodSigns(arr: [0, 1]) == 0
 prodSigns(arr: [] as [Int]) == nil
 */
func prodSigns(arr: [Int]) -> Int? {

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

Problem #145 Experiment #42

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {





```

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {





Here is the solution: (1 * (1 * (1 * (1 * 1 + 2 * (1 + 2 * 1 *

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {





```

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {





```

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {





```

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {





```

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {





```

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {





Here is the solution: 
 // function to calculate the product of magnitudes of signs of magnitudes of each number in array
- product of integers and

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {





```

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {




```

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

Problem #145 Experiment #43

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitudes = 0
    for num in arr {
        productSign *= num
        sumMagnitudes += abs(num)
    }
    return productSign * sumMagnitudes
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitudes = 0
    for num in arr {
        productSign *= num
        sumMagnitudes += abs(num)
    }
    return productSign * sumMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 1 : num
    }
    
    return sum * product
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 1 : num
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitudes = 0
    
    for num in arr {
        sumMagnitudes += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    
    return productSign * sumMagnitudes
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitudes = 0
    
    for num in arr {
        sumMagnitudes += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    
    return productSign * sumMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signProduct = 1
    var magnitudeSum = 0
    for num in arr {
        magnitudeSum += abs(num)
        signProduct *= num < 0 ? -1 : 1
    }
    return signProduct * magnitudeSum
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signProduct = 1
    var magnitudeSum = 0
    for num in arr {
        magnitudeSum += abs(num)
        signProduct *= num < 0 ? -1 : 1
    }
    return signProduct * magnitudeSum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitudes = 0
    for num in arr {
        sumMagnitudes += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    return productSign * sumMagnitudes
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitudes = 0
    for num in arr {
        sumMagnitudes += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    return productSign * sumMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitude = 0
    
    for num in arr {
        sumMagnitude += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    
    return productSign * sumMagnitude
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitude = 0
    
    for num in arr {
        sumMagnitude += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    
    return productSign * sumMagnitude
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num < 0 ? -1 : 1
    }
    
    return sum * product
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num < 0 ? -1 : 1
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num < 0 ? -1 : 1
    }
    
    return sum * product
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num < 0 ? -1 : 1
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitude = 0
    for num in arr {
        sumMagnitude += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    return productSign * sumMagnitude
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitude = 0
    for num in arr {
        sumMagnitude += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    return productSign * sumMagnitude
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 1 : num
    }
    return sum * product
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 1 : num
    }
    return sum * product
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #46

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num < 0 {
            prod *= -1
        } else if num > 0 {
            prod *= 1
        } else {
            return 0
        }
        sum += abs(num)
    }
    
    return sum * prod
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num < 0 {
            prod *= -1
        } else if num > 0 {
            prod *= 1
        } else {
            return 0
        }
        sum += abs(num)
    }
    
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num < 0 {
            prod *= -1
        } else if num > 0 {
            prod *= 1
        } else {
            return 0
        }
        sum += abs(num)
    }
    
    return sum * prod
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num < 0 {
            prod *= -1
        } else if num > 0 {
            prod *= 1
        } else {
            return 0
        }
        sum += abs(num)
    }
    
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard let nonEmptyArr = arr.first else { return nil }
    
    var sumOfMagnitudes = 0
    var prodOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        prodOfSigns *= num >= 0 ? 1 : -1
    }
    
    return sumOfMagnitudes * prodOfSigns
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard let nonEmptyArr = arr.first else { return nil }
    
    var sumOfMagnitudes = 0
    var prodOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        prodOfSigns *= num >= 0 ? 1 : -1
    }
    
    return sumOfMagnitudes * prodOfSigns
}
```

guard let nonEmptyArr = arr.first else { return nil } // value 'nonEmptyArr' was defined but never used; consider replacing with boolean test

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num < 0 {
            prod *= -1
        } else if num > 0 {
            prod *= 1
        } else {
            return 0
        }
        sum += abs(num)
    }
    
    return sum * prod
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num < 0 {
            prod *= -1
        } else if num > 0 {
            prod *= 1
        } else {
            return 0
        }
        sum += abs(num)
    }
    
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num < 0 {
            prod *= -1
        } else if num > 0 {
            prod *= 1
        } else {
            return 0
        }
        sum += abs(num)
    }
    
    return sum * prod
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num < 0 {
            prod *= -1
        } else if num > 0 {
            prod *= 1
        } else {
            return 0
        }
        sum += abs(num)
    }
    
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard let nonEmptyArr = arr.first else { return nil }
    
    var sumOfMagnitudes = 0
    var prodOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        prodOfSigns *= num >= 0 ? 1 : -1
    }
    
    return sumOfMagnitudes * prodOfSigns
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard let nonEmptyArr = arr.first else { return nil }
    
    var sumOfMagnitudes = 0
    var prodOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        prodOfSigns *= num >= 0 ? 1 : -1
    }
    
    return sumOfMagnitudes * prodOfSigns
}
```

guard let nonEmptyArr = arr.first else { return nil } // value 'nonEmptyArr' was defined but never used; consider replacing with boolean test

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}
```

Problem #145 Experiment #47

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

productOfSigns *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num.sign
    }
    
    return sum * product
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num.sign
    }
    
    return sum * product
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

productOfSigns *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

productOfSigns *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

productOfSigns *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

productOfSigns *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

productOfSigns *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        productOfSigns *= num.sign
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

productOfSigns *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num.sign
    }
    
    return sum * product
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num.sign
    }
    
    return sum * product
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num < 0 {
            productOfSigns *= -1
        } else if num > 0 {
            productOfSigns *= 1
        } else {
            productOfSigns *= 0
        }
        
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

<｜begin▁of▁sentence｜>You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num < 0 {
            productOfSigns *= -1
        } else if num > 0 {
            productOfSigns *= 1
        } else {
            productOfSigns *= 0
        }
        
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

Problem #145 Experiment #48

import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }

        sum += abs(num)
    }

    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }

        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
import Foundation

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #51

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            productOfSigns *= -1
        }
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            productOfSigns *= -1
        }
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            productOfSigns *= -1
        }
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            productOfSigns *= -1
        }
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= num > 0 ? 1 : -1
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= num > 0 ? 1 : -1
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

Problem #145 Experiment #52

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

Problem #145 Experiment #77

func prodSigns(arr: [Int]) -> Int? {
    guard let first = arr.first else { return nil }
    let product = arr.reduce(1) { $0 * $1 }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return first * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard let first = arr.first else { return nil }
    let product = arr.reduce(1) { $0 * $1 }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return first * product
}
```

let sum = arr.reduce(0) { $0 + abs($1) } // initialization of immutable value 'sum' was never used; consider replacing with assignment to '_' or removing it

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    
    var product: Int = 1
    var sum: Int = 0
    
    for num in arr {
        product *= num < 0 ? -1 : 1
        sum += abs(num)
    }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    
    var product: Int = 1
    var sum: Int = 0
    
    for num in arr {
        product *= num < 0 ? -1 : 1
        sum += abs(num)
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard let first = arr.first else { return nil }
    let product = arr.reduce(1) { $0 * $1 }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard let first = arr.first else { return nil }
    let product = arr.reduce(1) { $0 * $1 }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}
```

guard let first = arr.first else { return nil } // value 'first' was defined but never used; consider replacing with boolean test

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard let first = arr.first else { return nil }
    
    let product = arr.reduce(1) { $0 * $1 }
    let sum = arr.reduce(0) { $0 + abs($1) }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard let first = arr.first else { return nil }
    
    let product = arr.reduce(1) { $0 * $1 }
    let sum = arr.reduce(0) { $0 + abs($1) }
    
    return sum * product
}
```

guard let first = arr.first else { return nil } // value 'first' was defined but never used; consider replacing with boolean test

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num > 0 ? 1 : -1
        sum += abs(num)
    }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num > 0 ? 1 : -1
        sum += abs(num)
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        sum += abs(num)
        product *= (num == 0 ? 1 : num / abs(num))
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        sum += abs(num)
        product *= (num == 0 ? 1 : num / abs(num))
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            sum = 0
            break
        }
        
        product *= num < 0 ? -1 : 1
        sum += abs(num)
    }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            sum = 0
            break
        }
        
        product *= num < 0 ? -1 : 1
        sum += abs(num)
    }
    
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard let first = arr.first else { return nil }
    
    let product = arr.reduce(1) { $0 * $1 }
    let sum = arr.reduce(0) { $0 + abs($1) }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard let first = arr.first else { return nil }
    
    let product = arr.reduce(1) { $0 * $1 }
    let sum = arr.reduce(0) { $0 + abs($1) }
    
    return sum * product
}
```

guard let first = arr.first else { return nil } // value 'first' was defined but never used; consider replacing with boolean test

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            sum += 0
        } else {
            sum += abs(num)
            product *= num < 0 ? -1 : 1
        }
    }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            sum += 0
        } else {
            sum += abs(num)
            product *= num < 0 ? -1 : 1
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #78

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        sum += arr[i].magnitude
        if arr[i] < 0 {
            product *= -1
        }
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        sum += arr[i].magnitude
        if arr[i] < 0 {
            product *= -1
        }
    }
    return sum * product
}
```

sum += arr[i].magnitude // cannot convert value of type 'UInt' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        }
    }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            product = 0
        } else if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            product = 0
        } else if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            product = 0
            break
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            product = 0
            break
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        
        if arr[i] > 0 {
            sum += arr[i]
        } else {
            sum -= arr[i]
        }
        
        product *= arr[i]
    }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        
        if arr[i] > 0 {
            sum += arr[i]
        } else {
            sum -= arr[i]
        }
        
        product *= arr[i]
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    var sum = 0
    var prod = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        } else if arr[i] > 0 {
            prod *= 1
        } else if arr[i] < 0 {
            prod *= -1
        }
        sum += abs(arr[i])
    }
    return sum * prod
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    var sum = 0
    var prod = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        } else if arr[i] > 0 {
            prod *= 1
        } else if arr[i] < 0 {
            prod *= -1
        }
        sum += abs(arr[i])
    }
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}
```

Problem #145 Experiment #79

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : -1
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : -1
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : -1 // integer literal is unused

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : -1
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : -1
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : -1 // integer literal is unused

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : -1
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : -1
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : -1 // integer literal is unused

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = num > 0? 1 : -1
        sum += abs(num) * sign
        product *= sign
    }
    
    return sum * product
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = num > 0? 1 : -1
        sum += abs(num) * sign
        product *= sign
    }
    
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : -1 // integer literal is unused

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = num > 0? 1 : -1
        sum += abs(num) * sign
        product *= sign
    }
    
    return sum * product
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = num > 0? 1 : -1
        sum += abs(num) * sign
        product *= sign
    }
    
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : -1 // integer literal is unused

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

Problem #145 Experiment #87

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, *)
    return arr.reduce(0, +) * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, *)
    return arr.reduce(0, +) * product
}
```
### Problem

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num > 0 ? 1 : num < 0 ? -1 : 0
        sum += abs(num)
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num > 0 ? 1 : num < 0 ? -1 : 0
        sum += abs(num)
    }
    return sum * product
}
```
### Problem

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num == 0 ? 0 : num > 0 ? 1 : -1
    }
    return result
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num == 0 ? 0 : num > 0 ? 1 : -1
    }
    return result
}
```
### Link

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var product = 1
    for num in arr {
        product *= num
        result += abs(num) * product
    }
    return result
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var product = 1
    for num in arr {
        product *= num
        result += abs(num) * product
    }
    return result
}
```
### Problem

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(0) { $0 * $1 }
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(0) { $0 * $1 }
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for i in arr {
        result *= i < 0 ? -1 : 1
    }
    return result
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for i in arr {
        result *= i < 0 ? -1 : 1
    }
    return result
}
```
### Problem

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(0) { $0 + $1 > 0 ? $1 : 0 }
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(0) { $0 + $1 > 0 ? $1 : 0 }
}
```
### Ex

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for i in arr {
        product *= i < 0 ? -1 : 1
        sum += abs(i)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for i in arr {
        product *= i < 0 ? -1 : 1
        sum += abs(i)
    }
    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for i in arr {
        product *= i > 0 ? 1 : i < 0 ? -1 : 0
        sum += abs(i)
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for i in arr {
        product *= i > 0 ? 1 : i < 0 ? -1 : 0
        sum += abs(i)
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(0) { $0 * $1 }
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(0) { $0 * $1 }
}
```
### Ex

 // XCTAssertTrue failed

Problem #145 Experiment #88

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        result *= abs(i)
        if i < 0 {
            sign *= -1
        }
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        result *= abs(i)
        if i < 0 {
            sign *= -1
        }
    }
    return result * sign
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num > 0 ? 1 : num == 0 ? 0 : -1
        sum += abs(num)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num > 0 ? 1 : num == 0 ? 0 : -1
        sum += abs(num)
    }
    return product * sum
}
```
### Link

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum -= num
        }
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum -= num
        }
    }
    return sum * product
}
```
### Link

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for num in arr {
        if num == 0 {
            sign = 0
        } else if num < 0 {
            sign = -sign
        }
        result *= abs(num)
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for num in arr {
        if num == 0 {
            sign = 0
        } else if num < 0 {
            sign = -sign
        }
        result *= abs(num)
    }
    return result * sign
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        result *= abs(i)
        sign *= (i == 0) ? 0 : (i > 0) ? 1 : -1
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        result *= abs(i)
        sign *= (i == 0) ? 0 : (i > 0) ? 1 : -1
    }
    return result * sign
}
```
### Link

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        result *= abs(i)
        if i < 0 {
            sign *= -1
        }
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        result *= abs(i)
        if i < 0 {
            sign *= -1
        }
    }
    return result * sign
}
```
### Link

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += num > 0 ? 1 : (num < 0 ? -1 : 0)
        product *= num > 0 ? num : 1
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += num > 0 ? 1 : (num < 0 ? -1 : 0)
        product *= num > 0 ? num : 1
    }
    return sum * product
}
```
### Link

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            sign = 0
        } else if i < 0 {
            sign = -sign
        }
        result *= abs(i)
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            sign = 0
        } else if i < 0 {
            sign = -sign
        }
        result *= abs(i)
    }
    return result * sign
}
```
### Link

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in 0..<arr.count {
        result *= abs(arr[i])
        if arr[i] < 0 {
            sign *= -1
        } else if arr[i] > 0 {
            sign *= 1
        }
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in 0..<arr.count {
        result *= abs(arr[i])
        if arr[i] < 0 {
            sign *= -1
        } else if arr[i] > 0 {
            sign *= 1
        }
    }
    return result * sign
}
```
### Link

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            sign = 0
        } else if i < 0 {
            sign *= -1
        }
        result *= abs(i)
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            sign = 0
        } else if i < 0 {
            sign *= -1
        }
        result *= abs(i)
    }
    return result * sign
}
```
### Link

 // XCTAssertTrue failed

Problem #145 Experiment #101

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var result: Int = 1
    for element in arr {
        if element < 0 {
            result *= -1
        }
    }
    return result * arr.reduce(0, +)
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var result: Int = 1
    for element in arr {
        if element < 0 {
            result *= -1
        }
    }
    return result * arr.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for element in arr {
        if element < 0 {
            result *= -1
        }
    }
    return result * arr.reduce(0, +)
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for element in arr {
        if element < 0 {
            result *= -1
        }
    }
    return result * arr.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(0) { $0 + abs($1) * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(0) { $0 + abs($1) * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result: Int = 1
    for num in arr {
        result *= num < 0 ? -1 : 1
    }
    return result * arr.reduce(0, { $0 + abs($1) })
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result: Int = 1
    for num in arr {
        result *= num < 0 ? -1 : 1
    }
    return result * arr.reduce(0, { $0 + abs($1) })
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let products = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return products * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let products = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return products * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for element in arr {
        result *= element >= 0 ? 1 : -1
    }
    return result * arr.reduce(0, +)
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for element in arr {
        result *= element >= 0 ? 1 : -1
    }
    return result * arr.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let products = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return products * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let products = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return products * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let products = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return products * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let products = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return products * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sum = 0
    for element in arr {
        if element > 0 {
            result *= 1
            sum += element
        } else if element < 0 {
            result *= -1
            sum += element
        } else {
            result *= 0
            sum += element
        }
    }
    return result * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sum = 0
    for element in arr {
        if element > 0 {
            result *= 1
            sum += element
        } else if element < 0 {
            result *= -1
            sum += element
        } else {
            result *= 0
            sum += element
        }
    }
    return result * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(0) { $0 + abs($1) * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(0) { $0 + abs($1) * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #104

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    let sumOfMagnitudes = arr.reduce(0) { $0 + $1.magnitude }
    let productOfSigns = arr.reduce(1) { $0 * ($1 == 0 ? 0 : ($1 > 0 ? 1 : -1)) }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    let sumOfMagnitudes = arr.reduce(0) { $0 + $1.magnitude }
    let productOfSigns = arr.reduce(1) { $0 * ($1 == 0 ? 0 : ($1 > 0 ? 1 : -1)) }
    
    return sumOfMagnitudes * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: Optional(9)
print(prodSigns(arr: [0, 1]))         // Output: Optional(0)
print(prodSigns(arr: []))             // Output: nil
```

This function takes an array of integers and calculates the sum of magnitudes of integers multiplied by the product of all signs of each number. The sign of a number is represented by 1, -1 or 0. If the array is empty, it returns nil.

The function first calculates the sum of magnitudes of the integers in the array using the reduce method. Then, it calculates the product of all signs by multiplying all the signs of the numbers in the array. Finally, it multiplies the sum of magnitudes by the product of all signs and returns the result.

return sumOfMagnitudes * productOfSigns // cannot convert value of type 'UInt' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        product *= num > 0 ? 1 : num < 0 ? -1 : 0
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        product *= num > 0 ? 1 : num < 0 ? -1 : 0
        sum += abs(num)
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 == 0 ? 0 : -1) }
    let sumOfMagnitudes = arr.reduce(0) { $0 + abs($1) }
    return productOfSigns * sumOfMagnitudes
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 == 0 ? 0 : -1) }
    let sumOfMagnitudes = arr.reduce(0) { $0 + abs($1) }
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        let sign = num > 0 ? 1 : num < 0 ? -1 : 0
        sum += sign
        product *= sign
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        let sign = num > 0 ? 1 : num < 0 ? -1 : 0
        sum += sign
        product *= sign
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        let sign = num > 0 ? 1 : num < 0 ? -1 : 0
        product *= sign
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        let sign = num > 0 ? 1 : num < 0 ? -1 : 0
        product *= sign
        sum += abs(num)
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    let sumOfMagnitudes = arr.reduce(0) { $0 + abs($1) }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 == 0 ? 0 : -1) }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    let sumOfMagnitudes = arr.reduce(0) { $0 + abs($1) }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 == 0 ? 0 : -1) }
    
    return sumOfMagnitudes * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: Optional(9)
print(prodSigns(arr: [0, 1]))        // Output: Optional(0)
print(prodSigns(arr: []))            // Output: nil
```

This function takes an array of integers and calculates the sum of magnitudes of integers multiplied by the product of all signs of each number in the array. The sign of a number is represented by 1, -1 or 0. If the array is empty, it returns nil.

The function first calculates the sum of magnitudes of the integers in the array using the `reduce` method with a closure that takes the absolute value of each element. It then calculates the product of all signs of the numbers in the array using the `reduce` method with a closure that multiplies the sign of each element. Finally, it multiplies the sum of magnitudes by the product of all signs to get the final result.

The function returns the result as an optional integer, which is `nil` if the array is empty.

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    let magnitude = arr.reduce(0) { $0 + abs($1) }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 == 0 ? 0 : -1) }
    
    return magnitude * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    let magnitude = arr.reduce(0) { $0 + abs($1) }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 == 0 ? 0 : -1) }
    
    return magnitude * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: Optional(9)
print(prodSigns(arr: [0, 1]))        // Output: Optional(0)
print(prodSigns(arr: []))            // Output: nil
```

This function takes an array of integers and calculates the sum of magnitudes of integers multiplied by the product of all signs of each number. The sign of a number is represented by 1 for positive, -1 for negative, and 0 for zero. The magnitude of a number is its absolute value.

The function first calculates the magnitude of all numbers in the array by summing up the absolute values of the numbers. It then calculates the product of all signs of the numbers by multiplying all the signs. Finally, it multiplies the magnitude by the product of all signs to get the final result.

The function returns nil if the input array is empty.

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        let sign = num > 0 ? 1 : num < 0 ? -1 : 0
        productOfSigns *= sign
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        let sign = num > 0 ? 1 : num < 0 ? -1 : 0
        productOfSigns *= sign
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))        // Output: 0
print(prodSigns(arr: []))            // Output: nil
```

This function takes an array of integers and calculates the sum of magnitudes of integers multiplied by the product of all signs of each number in the array. The sign of a number is represented by 1, -1 or 0. If the array is empty, it returns nil.

The function iterates over each number in the array, calculates the sign and updates the product of signs. It also accumulates the sum of magnitudes. Finally, it returns the product of signs multiplied by the sum of magnitudes.

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        let sign = number.signum()
        sumOfMagnitudes += abs(number)
        productOfSigns *= sign
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        let sign = number.signum()
        sumOfMagnitudes += abs(number)
        productOfSigns *= sign
    }
    
    return sumOfMagnitudes * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))        // Output: 0
print(prodSigns(arr: []))            // Output: nil
```

This function takes an array of integers and calculates the sum of magnitudes of integers multiplied by the product of all signs of each number in the array. The sign of a number is represented by 1, -1 or 0. If the array is empty, it returns nil.

The function first checks if the array is empty and returns nil if it is. It then iterates through each number in the array, calculates the sum of magnitudes of integers and the product of all signs. The sum of magnitudes is calculated by adding the absolute value of each number to the sum. The product of all signs is calculated by multiplying the sign of each number to the product. Finally, it returns the product of the sum of magnitudes and the product of all signs.

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        let sign = num > 0 ? 1 : num < 0 ? -1 : 0
        productOfSigns *= sign
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        let sign = num > 0 ? 1 : num < 0 ? -1 : 0
        productOfSigns *= sign
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))        // Output: 0
print(prodSigns(arr: []))            // Output: nil
```

This function takes an array of integers and calculates the sum of magnitudes of integers multiplied by the product of all signs of each number in the array. The sign of a number is represented by 1, -1 or 0. If the array is empty, it returns nil.

The function iterates through the array, calculates the sum of magnitudes and the product of signs, and then multiplies them together to get the final result.

Problem #145 Experiment #107

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(1, { $0 * $1 })
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    return arr.reduce(1, { $0 * $1 })
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var result = 0
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
            continue
        }
        result += arr[i] * sign
        sign *= -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var result = 0
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
            continue
        }
        result += arr[i] * sign
        sign *= -1
    }
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    
    var result = 0
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
            continue
        }
        result += arr[i] * sign
        sign *= -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    
    var result = 0
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
            continue
        }
        result += arr[i] * sign
        sign *= -1
    }
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    var product = 1
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
            continue
        }
        product *= arr[i]
        if arr[i] < 0 {
            sign *= -1
        }
    }
    result += sign * product
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    var product = 1
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
            continue
        }
        product *= arr[i]
        if arr[i] < 0 {
            sign *= -1
        }
    }
    result += sign * product
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            return nil
        }
        product *= i
    }
    for i in arr {
        sum += i * product
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            return nil
        }
        product *= i
    }
    for i in arr {
        sum += i * product
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
            continue
        }
        result += arr[i] * sign
        sign *= -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
            continue
        }
        result += arr[i] * sign
        sign *= -1
    }
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for i in arr {
        if i != 0 {
            product *= i
        }
        sum += product
    }
    
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for i in arr {
        if i != 0 {
            product *= i
        }
        sum += product
    }
    
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for i in arr {
        product *= i
    }
    for i in arr {
        if i == 0 {
            return 0
        }
        sum += i * product
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for i in arr {
        product *= i
    }
    for i in arr {
        if i == 0 {
            return 0
        }
        sum += i * product
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] != 0 {
            product *= arr[i]
        }
    }
    for i in 0..<arr.count {
        if arr[i] != 0 {
            sum += product / arr[i]
        }
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] != 0 {
            product *= arr[i]
        }
    }
    for i in 0..<arr.count {
        if arr[i] != 0 {
            sum += product / arr[i]
        }
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sum += 0
        } else {
            product *= arr[i]
            sum += product
        }
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sum += 0
        } else {
            product *= arr[i]
            sum += product
        }
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

Problem #145 Experiment #113

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            return nil
        }
        if i < 0 {
            product *= -1
        }
        sum += i * product
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            return nil
        }
        if i < 0 {
            product *= -1
        }
        sum += i * product
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        product *= arr[i]
    }
    for i in 0..<arr.count {
        sum += arr[i] * product
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        product *= arr[i]
    }
    for i in 0..<arr.count {
        sum += arr[i] * product
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        product *= arr[i]
    }
    for i in 0..<arr.count {
        sum += arr[i] * product
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        product *= arr[i]
    }
    for i in 0..<arr.count {
        sum += arr[i] * product
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var result = 0
    var sign = 1
    
    for num in arr {
        result += num * sign
        sign *= -1
    }
    
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var result = 0
    var sign = 1
    
    for num in arr {
        result += num * sign
        sign *= -1
    }
    
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sum += 0
        } else {
            product *= arr[i]
            if arr[i] < 0 {
                sum += product
            } else {
                sum -= product
            }
        }
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sum += 0
        } else {
            product *= arr[i]
            if arr[i] < 0 {
                sum += product
            } else {
                sum -= product
            }
        }
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
        } else {
            result += sign * arr[i]
            sign *= -1
        }
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 0
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
        } else {
            result += sign * arr[i]
            sign *= -1
        }
    }
    return result
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for i in arr {
        result *= i
    }
    var sum = 0
    for i in arr {
        sum += i * result
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for i in arr {
        result *= i
    }
    var sum = 0
    for i in arr {
        sum += i * result
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for i in arr {
        result *= i
    }
    var sum = 0
    for i in arr {
        sum += i * result
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for i in arr {
        result *= i
    }
    var sum = 0
    for i in arr {
        sum += i * result
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            return 0
        }
        product *= i
    }
    for i in arr {
        sum += i * product
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            return 0
        }
        product *= i
    }
    for i in arr {
        sum += i * product
    }
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    
    var sum = 0
    var product = 1
    var sign = 1
    
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
        } else {
            product *= arr[i]
        }
    }
    
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
        } else {
            sum += arr[i] * sign
        }
    }
    
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    
    var sum = 0
    var product = 1
    var sign = 1
    
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
        } else {
            product *= arr[i]
        }
    }
    
    for i in 0..<arr.count {
        if arr[i] == 0 {
            sign = 0
        } else {
            sum += arr[i] * sign
        }
    }
    
    return sum
}
<|file_separator|>

 // XCTAssertTrue failed

Problem #145 Experiment #114

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count != 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count != 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    let sum = arr.reduce(0, +)
    let product = arr.reduce(1, *)
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    let sum = arr.reduce(0, +)
    let product = arr.reduce(1, *)
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num != 0 {
            product *= num > 0 ? 1 : -1
        }
        sum += abs(num)
    }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num != 0 {
            product *= num > 0 ? 1 : -1
        }
        sum += abs(num)
    }
    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count != 0 else {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for number in arr {
        if number != 0 {
            product *= number > 0 ? 1 : -1
            sum += abs(number)
        }
    }
    
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count != 0 else {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for number in arr {
        if number != 0 {
            product *= number > 0 ? 1 : -1
            sum += abs(number)
        }
    }
    
    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count != 0 else {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for i in 0..<arr.count {
        if arr[i] != 0 {
            sum += arr[i]
            product *= arr[i] > 0 ? 1 : -1
        }
    }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count != 0 else {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for i in 0..<arr.count {
        if arr[i] != 0 {
            sum += arr[i]
            product *= arr[i] > 0 ? 1 : -1
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count != 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 1 : num > 0 ? 1 : -1
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count != 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 1 : num > 0 ? 1 : -1
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        sum += i
        product *= i == 0 ? 1 : i > 0 ? 1 : -1
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        sum += i
        product *= i == 0 ? 1 : i > 0 ? 1 : -1
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num > 0 {
            sum += num
            product *= 1
        } else if num < 0 {
            sum -= num
            product *= -1
        } else {
            product *= 0
        }
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num > 0 {
            sum += num
            product *= 1
        } else if num < 0 {
            sum -= num
            product *= -1
        } else {
            product *= 0
        }
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num == 0 {
            sum += 0
        } else if num < 0 {
            sum -= num
            product *= -1
        } else {
            sum += num
        }
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num == 0 {
            sum += 0
        } else if num < 0 {
            sum -= num
            product *= -1
        } else {
            sum += num
        }
    }
    return sum * product
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #115

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for _, i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            sum += i
        } else {
            sum -= i
        }
        product *= i
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for _, i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            sum += i
        } else {
            sum -= i
        }
        product *= i
    }
    return sum * product
}
// Test
print(prodSigns(arr: [1, 2, 2, -4]))
print(prodSigns(arr: [0, 1]))
print(prodSigns(arr: [] as [Int]))
```

for _, i in arr { // expected Sequence expression for for-each loop

for _, i in arr { // expected 'in' after for-each pattern

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        sum += arr[i] * arr[i]
        product *= arr[i]
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        sum += arr[i] * arr[i]
        product *= arr[i]
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    for i in 0..<arr.count {
        sum += arr[i] * arr[i] * arr[i]
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    for i in 0..<arr.count {
        sum += arr[i] * arr[i] * arr[i]
    }
    return sum
}
```

if arr.isEmpty() { // cannot call value of non-function type 'Bool'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    var product = 1
    for _, num in arr {
        sum += num
        product *= num
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    var product = 1
    for _, num in arr {
        sum += num
        product *= num
    }
    return sum * product
}
// Test cases:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
```

if arr.isEmpty() { // cannot call value of non-function type 'Bool'

for _, num in arr { // expected 'in' after for-each pattern

for _, num in arr { // expected Sequence expression for for-each loop

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for _, num in arr {
        if num == 0 {
            return 0
        }
        sum += num
        product *= num
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for _, num in arr {
        if num == 0 {
            return 0
        }
        sum += num
        product *= num
    }
    return sum * product
}
```

for _, num in arr { // expected 'in' after for-each pattern

for _, num in arr { // expected Sequence expression for for-each loop

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    for i in 0..<arr.count {
        sum += arr[i] * arr[i] * arr[i]
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    for i in 0..<arr.count {
        sum += arr[i] * arr[i] * arr[i]
    }
    return sum
}
```

if arr.isEmpty() { // cannot call value of non-function type 'Bool'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        sum += arr[i]
        product *= arr[i]
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        sum += arr[i]
        product *= arr[i]
    }
    return sum * product
}
// ```

if arr.isEmpty() { // cannot call value of non-function type 'Bool'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    for i in 0..<arr.count {
        sum += arr[i] * arr[i]
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    for i in 0..<arr.count {
        sum += arr[i] * arr[i]
    }
    return sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    for i in 0..<arr.count {
        sum += arr[i] * arr[i] * arr[i]
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    for i in 0..<arr.count {
        sum += arr[i] * arr[i] * arr[i]
    }
    return sum
}
```

if arr.isEmpty() { // cannot call value of non-function type 'Bool'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    for i in arr {
        sum += i * i
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty() {
        return nil
    }
    var sum = 0
    for i in arr {
        sum += i * i
    }
    return sum
}
```

if arr.isEmpty() { // cannot call value of non-function type 'Bool'

Problem #145 Experiment #116

func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty {
    return nil
  }
  
  var sum = 0
  var product = 1
  
  for num in arr {
    switch num {
    case 0:
      product = 0
    case let n where n > 0:
      sum += n
      product *= 1
    case let n where n < 0:
      sum -= n
      product *= -1
    }
  }
  
  return product == 0 ? 0 : product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty {
    return nil
  }
  
  var sum = 0
  var product = 1
  
  for num in arr {
    switch num {
    case 0:
      product = 0
    case let n where n > 0:
      sum += n
      product *= 1
    case let n where n < 0:
      sum -= n
      product *= -1
    }
  }
  
  return product == 0 ? 0 : product * sum
}
```

switch num { // switch must be exhaustive

func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty { return nil }
  var productOfSigns = 1
  var sumOfMagnitudes = 0
  for number in arr {
    if number == 0 {
      productOfSigns = 0
      sumOfMagnitudes = 0
      break
    } else {
      productOfSigns *= (number > 0) ? 1 : -1
      sumOfMagnitudes += abs(number)
    }
  }
  return productOfSigns * sumOfMagnitudes
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty { return nil }
  var productOfSigns = 1
  var sumOfMagnitudes = 0
  for number in arr {
    if number == 0 {
      productOfSigns = 0
      sumOfMagnitudes = 0
      break
    } else {
      productOfSigns *= (number > 0) ? 1 : -1
      sumOfMagnitudes += abs(number)
    }
  }
  return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num > 0 ? 1 : (num < 0 ? -1 : 0)
        sum += abs(num)
    }
    
    return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num > 0 ? 1 : (num < 0 ? -1 : 0)
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
  guard !arr.isEmpty else { return nil }
  var sum = 0
  var product = 1
  for num in arr {
    sum += abs(num)
    product *= (num == 0 ? 1 : num > 0 ? 1 : -1)
  }
  return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
  guard !arr.isEmpty else { return nil }
  var sum = 0
  var product = 1
  for num in arr {
    sum += abs(num)
    product *= (num == 0 ? 1 : num > 0 ? 1 : -1)
  }
  return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
  guard !arr.isEmpty else { return nil }
  
  var result = 1
  var zeroCount = 0
  
  for num in arr {
    if num == 0 {
      zeroCount += 1
    } else {
      result *= num > 0 ? 1 : -1
    }
  }
  
  if zeroCount > 1 {
    return 0
  } else if zeroCount == 1 {
    return 0
  } else {
    return result
  }
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
  guard !arr.isEmpty else { return nil }
  
  var result = 1
  var zeroCount = 0
  
  for num in arr {
    if num == 0 {
      zeroCount += 1
    } else {
      result *= num > 0 ? 1 : -1
    }
  }
  
  if zeroCount > 1 {
    return 0
  } else if zeroCount == 1 {
    return 0
  } else {
    return result
  }
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty { return nil }
  var sum = 0
  var product = 1
  for num in arr {
    product *= (num > 0) ? 1 : (num < 0) ? -1 : 0
    sum += abs(num)
  }
  return sum * product
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty { return nil }
  var sum = 0
  var product = 1
  for num in arr {
    product *= (num > 0) ? 1 : (num < 0) ? -1 : 0
    sum += abs(num)
  }
  return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty { return nil }
  var product = 1
  var sum = 0
  for num in arr {
    switch num {
    case 0:
      sum = 0
      product = 1
    case let x where x > 0:
      sum += x
      product *= 1
    case let x where x < 0:
      sum -= x
      product *= -1
    default:
      break
    }
  }
  return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty { return nil }
  var product = 1
  var sum = 0
  for num in arr {
    switch num {
    case 0:
      sum = 0
      product = 1
    case let x where x > 0:
      sum += x
      product *= 1
    case let x where x < 0:
      sum -= x
      product *= -1
    default:
      break
    }
  }
  return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var prod = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            sum = 0
            prod = 0
        } else {
            sum += abs(num)
            prod *= (num > 0 ? 1 : -1)
        }
    }
    return sum * prod
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var prod = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            sum = 0
            prod = 0
        } else {
            sum += abs(num)
            prod *= (num > 0 ? 1 : -1)
        }
    }
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num != 0 {
            product *= (num > 0 ? 1 : -1)
        }
        sum += abs(num)
    }
    return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num != 0 {
            product *= (num > 0 ? 1 : -1)
        }
        sum += abs(num)
    }
    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
  guard !arr.isEmpty else { return nil }
  
  var result = 1
  var zeroCount = 0
  
  for num in arr {
    if num == 0 {
      zeroCount += 1
    } else {
      result *= (num < 0) ? -1 : 1
    }
  }
  
  if zeroCount > 0 {
    return 0
  } else {
    return result
  }
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
  guard !arr.isEmpty else { return nil }
  
  var result = 1
  var zeroCount = 0
  
  for num in arr {
    if num == 0 {
      zeroCount += 1
    } else {
      result *= (num < 0) ? -1 : 1
    }
  }
  
  if zeroCount > 0 {
    return 0
  } else {
    return result
  }
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #117

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= (num > 0) ? 1 : (num < 0) ? -1 : 0
        sum += abs(num)
    }
    
    return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= (num > 0) ? 1 : (num < 0) ? -1 : 0
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= (num > 0 ? 1 : (num < 0 ? -1 : 0))
        sum += abs(num)
    }
    
    return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= (num > 0 ? 1 : (num < 0 ? -1 : 0))
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        product *= (num > 0) ? 1 : (num < 0) ? -1 : 0
        sum += abs(num)
    }

    return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        product *= (num > 0) ? 1 : (num < 0) ? -1 : 0
        sum += abs(num)
    }

    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= (num > 0 ? 1 : (num < 0 ? -1 : 0))
        sum += abs(num)
    }
    
    return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= (num > 0 ? 1 : (num < 0 ? -1 : 0))
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= (num > 0) ? 1 : (num < 0) ? -1 : 0
        sum += abs(num)
    }
    return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= (num > 0) ? 1 : (num < 0) ? -1 : 0
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= sign(num)
        sum += abs(num)
    }
    
    return product * sum
}

func sign(_ num: Int) -> Int {
    if num > 0 {
        return 1
    } else if num < 0 {
        return -1
    } else {
        return 0
    }
}

func abs(_ num: Int) -> Int {
    if num < 0 {
        return -num
    } else {
        return num
    }
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= sign(num)
        sum += abs(num)
    }
    
    return product * sum
}

func sign(_ num: Int) -> Int {
    if num > 0 {
        return 1
    } else if num < 0 {
        return -1
    } else {
        return 0
    }
}

func abs(_ num: Int) -> Int {
    if num < 0 {
        return -num
    } else {
        return num
    }
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }

    var product = 1
    var sum = 0

    for num in arr {
        product *= num > 0 ? 1 : -1
        sum += abs(num)
    }

    return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }

    var product = 1
    var sum = 0

    for num in arr {
        product *= num > 0 ? 1 : -1
        sum += abs(num)
    }

    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        product *= (num > 0 ? 1 : (num < 0 ? -1 : 0))
        sum += abs(num)
    }

    return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        product *= (num > 0 ? 1 : (num < 0 ? -1 : 0))
        sum += abs(num)
    }

    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    var product = 1
    var sum = 0

    for num in arr {
        product *= sign(num)
        sum += abs(num)
    }

    return product * sum
}

func sign(_ num: Int) -> Int {
    if num > 0 {
        return 1
    } else if num < 0 {
        return -1
    } else {
        return 0
    }
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    var product = 1
    var sum = 0

    for num in arr {
        product *= sign(num)
        sum += abs(num)
    }

    return product * sum
}

func sign(_ num: Int) -> Int {
    if num > 0 {
        return 1
    } else if num < 0 {
        return -1
    } else {
        return 0
    }
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        product *= num > 0 ? 1 : (num < 0 ? -1 : 0)
        sum += abs(num)
    }

    return product * sum
}

<start_of_turn>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<end_of_turn>
<start_of_turn>model
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        product *= num > 0 ? 1 : (num < 0 ? -1 : 0)
        sum += abs(num)
    }

    return product * sum
}
```

Problem #145 Experiment #118

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        let sign = num == 0 ? 0 : (num > 0 ? 1 : -1)
        product *= sign
        sum += abs(num) * sign
    }
    return sum * product
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        let sign = num == 0 ? 0 : (num > 0 ? 1 : -1)
        product *= sign
        sum += abs(num) * sign
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    return signs.reduce(1, *) * arr.reduce(0, +)
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    return signs.reduce(1, *) * arr.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0 ? 0 : ($0 > 0 ? 1 : -1) }
    return signs.reduce(1, *) * arr.reduce(0, +)
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0 ? 0 : ($0 > 0 ? 1 : -1) }
    return signs.reduce(1, *) * arr.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return sum * product
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    return signs.reduce(1, *) * arr.reduce(0, +)
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    return signs.reduce(1, *) * arr.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 1 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return sum * product
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 1 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return sum * product
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    return signs.reduce(1, *) * arr.reduce(0, +)
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    return signs.reduce(1, *) * arr.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return product * sum
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return product * sum
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num == 0 ? 0 : (num > 0 ? 1 : -1)
        sum += abs(num)
    }
    return product * sum
}
```

Problem #145 Experiment #119

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        signs.append(sign(num))
        product *= num
    }
    return signs.reduce(0, +) * product
}

func sign(num: Int) -> Int {
    if num > 0 { return 1 }
    if num < 0 { return -1 }
    return 0
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        signs.append(sign(num))
        product *= num
    }
    return signs.reduce(0, +) * product
}

func sign(num: Int) -> Int {
    if num > 0 { return 1 }
    if num < 0 { return -1 }
    return 0
}
```

signs.append(sign(num)) // missing argument label 'num:' in call

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        let sign = num > 0 ? 1 : (num < 0 ? -1 : 0)
        signs.append(sign)
        product *= sign
    }
    return signs.map { $0 * product }.reduce(0, +)
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        let sign = num > 0 ? 1 : (num < 0 ? -1 : 0)
        signs.append(sign)
        product *= sign
    }
    return signs.map { $0 * product }.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        if num == 0 {
            signs.append(0)
        } else if num > 0 {
            signs.append(1)
        } else {
            signs.append(-1)
        }
        product *= num
    }
    return signs.map { $0 * product }.reduce(0, +)
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        if num == 0 {
            signs.append(0)
        } else if num > 0 {
            signs.append(1)
        } else {
            signs.append(-1)
        }
        product *= num
    }
    return signs.map { $0 * product }.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        if num == 0 {
            signs.append(0)
        } else if num > 0 {
            signs.append(1)
        } else {
            signs.append(-1)
        }
        product *= num
    }
    return signs.reduce(0, +) * product
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        if num == 0 {
            signs.append(0)
        } else if num > 0 {
            signs.append(1)
        } else {
            signs.append(-1)
        }
        product *= num
    }
    return signs.reduce(0, +) * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        if num > 0 {
            signs.append(1)
        } else if num < 0 {
            signs.append(-1)
        } else {
            signs.append(0)
        }
        product *= num
    }
    return signs.reduce(0, +) * product
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        if num > 0 {
            signs.append(1)
        } else if num < 0 {
            signs.append(-1)
        } else {
            signs.append(0)
        }
        product *= num
    }
    return signs.reduce(0, +) * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    for num in arr {
        product *= num.signum()
    }
    return product
}

extension Int {
    func signum() -> Int {
        if self > 0 { return 1 }
        if self < 0 { return -1 }
        return 0
    }
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    for num in arr {
        product *= num.signum()
    }
    return product
}

extension Int {
    func signum() -> Int {
        if self > 0 { return 1 }
        if self < 0 { return -1 }
        return 0
    }
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum -= num
        } else {
            product *= 0
        }
    }
    return product * sum
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum -= num
        } else {
            product *= 0
        }
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        let sign = num > 0 ? 1 : (num < 0 ? -1 : 0)
        signs.append(sign)
        product *= sign
    }
    return signs.map { $0 * product }.reduce(0, +)
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        let sign = num > 0 ? 1 : (num < 0 ? -1 : 0)
        signs.append(sign)
        product *= sign
    }
    return signs.map { $0 * product }.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        let sign = num > 0 ? 1 : (num < 0 ? -1 : 0)
        product *= sign
        sum += abs(num)
    }
    return product * sum
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        let sign = num > 0 ? 1 : (num < 0 ? -1 : 0)
        product *= sign
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        if num == 0 {
            signs.append(0)
        } else if num > 0 {
            signs.append(1)
        } else {
            signs.append(-1)
        }
        product *= num
    }
    return signs.reduce(0, +) * product
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    var product = 1
    for num in arr {
        if num == 0 {
            signs.append(0)
        } else if num > 0 {
            signs.append(1)
        } else {
            signs.append(-1)
        }
        product *= num
    }
    return signs.reduce(0, +) * product
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #120

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    return signs.reduce(1, *) * magnitudes.reduce(0, +)
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    return signs.reduce(1, *) * magnitudes.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    return signs.reduce(1, *) * magnitudes.reduce(0, +)
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }

    return signs.reduce(1, *) * magnitudes.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    return signs.reduce(1, *) * magnitudes.reduce(0, +)
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    return signs.reduce(1, *) * magnitudes.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs: [Int] = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes: [Int] = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}

[INST] Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil [/INST] ```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let signs: [Int] = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes: [Int] = arr.map { abs($0) }

    let productOfSigns = signs.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return productOfSigns * sumOfMagnitudes
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #121

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    return positiveCount * negativeCount * (zeroCount + 1)
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count
    let zeroCount = arr.filter { $0 == 0 }.count
    return positiveCount * negativeCount * (zeroCount + 1)
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * product
}
```

product *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // expected expression

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // expected expression

product *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }

    var sum = 0
    var product = 1

    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }

    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }

    var sum = 0
    var product = 1

    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }

    return sum * product
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

product *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // expected expression

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * product
}
```

product *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // expected expression

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }

    var sum = 0
    var product = 1

    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }

    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }

    var sum = 0
    var product = 1

    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }

    return sum * product
}
```

product *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // expected expression

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }

    var sum = 0
    var product = 1

    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }

    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }

    var sum = 0
    var product = 1

    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }

    return sum * product
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

product *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // expected expression

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * product
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

product *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // expected expression

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * product
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0? 1 : num < 0? -1 : 0
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num > 0? 1 : num < 0? -1 : 0 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // expected expression

product *= num > 0? 1 : num < 0? -1 : 0 // integer literal is unused

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : num < 0? -1 : 0 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : num < 0? -1 : 0 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }

    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count

    return positiveCount * negativeCount * arr.reduce(1) { $0 * $1 }
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }

    let positiveCount = arr.filter { $0 > 0 }.count
    let negativeCount = arr.filter { $0 < 0 }.count

    return positiveCount * negativeCount * arr.reduce(1) { $0 * $1 }
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

Problem #145 Experiment #122

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num > 0? 1 : -1
            sum += abs(num)
        }
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num > 0? 1 : -1
            sum += abs(num)
        }
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num > 0? 1 : -1 // expected expression

product *= num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : -1 // integer literal is unused

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product *= 0
            break
        }
        product *= num > 0? 1 : -1
        sum += abs(num)
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product *= 0
            break
        }
        product *= num > 0? 1 : -1
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num > 0? 1 : -1 // integer literal is unused

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // expected expression

product *= num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += num
        } else {
            product *= 0
        }
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += num
        } else {
            product *= 0
        }
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num > 0? 1 : -1
            sum += abs(num)
        }
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else {
            product *= num > 0? 1 : -1
            sum += abs(num)
        }
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num > 0? 1 : -1 // expected expression

product *= num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : -1 // integer literal is unused

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product *= 0
            break
        } else if num > 0 {
            product *= 1
            sum += num
        } else {
            product *= -1
            sum -= num
        }
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            product *= 0
            break
        } else if num > 0 {
            product *= 1
            sum += num
        } else {
            product *= -1
            sum -= num
        }
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { // expected expression, var, let or case in 'guard' condition

Problem #145 Experiment #123

func prodSigns(arr: [Int]) -> Int? {
    guard let nonEmptyArr = arr.isEmpty ? nil : arr else { return nil }
    var sum = 0
    var product = 1
    for num in nonEmptyArr {
        sum += abs(num)
        product *= num >= 0 ? 1 : -1
    }
    return sum * product
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard let nonEmptyArr = arr.isEmpty ? nil : arr else { return nil }
    var sum = 0
    var product = 1
    for num in nonEmptyArr {
        sum += abs(num)
        product *= num >= 0 ? 1 : -1
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productSign = 1
    var sumMagnitude = 0
    
    for num in arr {
        if num > 0 {
            productSign *= 1
            sumMagnitude += num
        } else if num < 0 {
            productSign *= -1
            sumMagnitude += -num
        } else {
            return 0
        }
    }
    
    return productSign * sumMagnitude
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productSign = 1
    var sumMagnitude = 0
    
    for num in arr {
        if num > 0 {
            productSign *= 1
            sumMagnitude += num
        } else if num < 0 {
            productSign *= -1
            sumMagnitude += -num
        } else {
            return 0
        }
    }
    
    return productSign * sumMagnitude
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            product *= 1
        } else if num < 0 {
            sum += abs(num)
            product *= -1
        } else {
            return 0
        }
    }
    
    return sum * product
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            product *= 1
        } else if num < 0 {
            sum += abs(num)
            product *= -1
        } else {
            return 0
        }
    }
    
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += -num
        } else {
            return 0
        }
    }
    
    return product * sum
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += -num
        } else {
            return 0
        }
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            prod *= 1
        } else if num < 0 {
            sum += abs(num)
            prod *= -1
        } else {
            return 0
        }
    }
    
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num < 0 {
            prod *= -1
        } else if num > 0 {
            prod *= 1
        } else {
            return 0
        }
        sum += abs(num)
    }
    
    return sum * prod
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var prod = 1
    
    for num in arr {
        if num < 0 {
            prod *= -1
        } else if num > 0 {
            prod *= 1
        } else {
            return 0
        }
        sum += abs(num)
    }
    
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productSign = 1
    var sumMagnitude = 0
    
    for num in arr {
        if num > 0 {
            productSign *= 1
            sumMagnitude += num
        } else if num < 0 {
            productSign *= -1
            sumMagnitude += -num
        } else {
            return 0
        }
    }
    
    return productSign * sumMagnitude
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productSign = 1
    var sumMagnitude = 0
    
    for num in arr {
        if num > 0 {
            productSign *= 1
            sumMagnitude += num
        } else if num < 0 {
            productSign *= -1
            sumMagnitude += -num
        } else {
            return 0
        }
    }
    
    return productSign * sumMagnitude
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            product *= 1
        } else if num < 0 {
            sum += abs(num)
            product *= -1
        } else {
            return 0
        }
    }
    
    return sum * product
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            sum += num
            product *= 1
        } else if num < 0 {
            sum += abs(num)
            product *= -1
        } else {
            return 0
        }
    }
    
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        } else {
            return 0
        }
        
        sum += abs(num)
    }
    
    return sum * product
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        } else {
            return 0
        }
        
        sum += abs(num)
    }
    
    return sum * product
}
```

Problem #145 Experiment #124

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitudes = 0
    
    for num in arr {
        productSign *= num
        sumMagnitudes += abs(num)
    }
    
    return productSign * sumMagnitudes
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitudes = 0
    
    for num in arr {
        productSign *= num
        sumMagnitudes += abs(num)
    }
    
    return productSign * sumMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num < 0 ? -1 : 1
    }
    
    return sum * product
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num < 0 ? -1 : 1
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 1 : num
    }
    return sum * product
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 1 : num
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitude = 0
    
    for num in arr {
        sumMagnitude += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    
    return productSign * sumMagnitude
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitude = 0
    
    for num in arr {
        sumMagnitude += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    
    return productSign * sumMagnitude
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitude = 0
    
    for num in arr {
        sumMagnitude += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    
    return productSign * sumMagnitude
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitude = 0
    
    for num in arr {
        sumMagnitude += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    
    return productSign * sumMagnitude
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitudes = 0
    
    for num in arr {
        productSign *= num
        sumMagnitudes += abs(num)
    }
    
    return productSign * sumMagnitudes
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productSign = 1
    var sumMagnitudes = 0
    
    for num in arr {
        productSign *= num
        sumMagnitudes += abs(num)
    }
    
    return productSign * sumMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitudes = 0
    for num in arr {
        productSign *= num
        sumMagnitudes += abs(num)
    }
    return productSign * sumMagnitudes
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitudes = 0
    for num in arr {
        productSign *= num
        sumMagnitudes += abs(num)
    }
    return productSign * sumMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitudes = 0
    for num in arr {
        sumMagnitudes += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    return productSign * sumMagnitudes
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitudes = 0
    for num in arr {
        sumMagnitudes += abs(num)
        productSign *= num < 0 ? -1 : 1
    }
    return productSign * sumMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 1 : num
    }
    
    return sum * product
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 1 : num
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitude = 0
    for num in arr {
        productSign *= num
        sumMagnitude += abs(num)
    }
    return productSign * sumMagnitude
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var productSign = 1
    var sumMagnitude = 0
    for num in arr {
        productSign *= num
        sumMagnitude += abs(num)
    }
    return productSign * sumMagnitude
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #125

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // expected expression

result *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= num < 0? -1 : 1 // integer literal is unused

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // expected expression

result *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= num < 0? -1 : 1 // integer literal is unused

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // expected expression

result *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= num < 0? -1 : 1 // integer literal is unused

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num > 0? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num > 0? 1 : -1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

result *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

result *= num > 0? 1 : -1 // expected expression

result *= num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

result *= num > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

result *= num > 0? 1 : -1 // integer literal is unused

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // expected expression

result *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= num < 0? -1 : 1 // integer literal is unused

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // expected expression

result *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= num < 0? -1 : 1 // integer literal is unused

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num.sign
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num.sign
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // integer literal is unused

result *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= num < 0? -1 : 1 // expected expression

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var positive = 0
    var negative = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        }
        if num > 0 {
            positive += 1
        } else {
            negative += 1
        }
        product *= num
    }
    return product * (positive % 2 == 0? 1 : -1) * (negative % 2 == 0? 1 : -1)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var positive = 0
    var negative = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        }
        if num > 0 {
            positive += 1
        } else {
            negative += 1
        }
        product *= num
    }
    return product * (positive % 2 == 0? 1 : -1) * (negative % 2 == 0? 1 : -1)
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

return product * (positive % 2 == 0? 1 : -1) * (negative % 2 == 0? 1 : -1) // expected ',' separator

return product * (positive % 2 == 0? 1 : -1) * (negative % 2 == 0? 1 : -1) // cannot convert value of type '(Bool, Int)' to expected argument type 'Int'

return product * (positive % 2 == 0? 1 : -1) * (negative % 2 == 0? 1 : -1) // expected ',' separator

return product * (positive % 2 == 0? 1 : -1) * (negative % 2 == 0? 1 : -1) // cannot convert value of type '(Bool, Int)' to expected argument type 'Int'

return product * (positive % 2 == 0? 1 : -1) * (negative % 2 == 0? 1 : -1) // cannot use optional chaining on non-optional value of type 'Int'

return product * (positive % 2 == 0? 1 : -1) * (negative % 2 == 0? 1 : -1) // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num < 0? -1 : 1
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // expected expression

result *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

result *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

result *= num < 0? -1 : 1 // integer literal is unused

result *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

result *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

Problem #145 Experiment #126

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var prod = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            sign = 0
        } else if i > 0 {
            prod *= sign
        } else {
            sign = -sign
        }
    }
    return prod * sign
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var prod = 1
    var sign = 1
    for i in arr {
        if i == 0 {
            sign = 0
        } else if i > 0 {
            prod *= sign
        } else {
            sign = -sign
        }
    }
    return prod * sign
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for num in arr {
        if num == 0 {
            sign = 0
        } else {
            result *= sign
            sign *= num > 0? 1 : -1
        }
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for num in arr {
        if num == 0 {
            sign = 0
        } else {
            result *= sign
            sign *= num > 0? 1 : -1
        }
    }
    return result
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

sign *= num > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

sign *= num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

sign *= num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

sign *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

sign *= num > 0? 1 : -1 // expected expression

sign *= num > 0? 1 : -1 // integer literal is unused

sign *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            prod *= 0
        } else {
            prod *= i > 0? 1 : -1
        }
        sum += abs(i)
    }
    return prod * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            prod *= 0
        } else {
            prod *= i > 0? 1 : -1
        }
        sum += abs(i)
    }
    return prod * sum
}
```

prod *= i > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

prod *= i > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

prod *= i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

prod *= i > 0? 1 : -1 // expected expression

prod *= i > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

prod *= i > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

prod *= i > 0? 1 : -1 // integer literal is unused

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        prod *= i < 0? -1 : 1
        sum += abs(i)
    }
    return prod * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        prod *= i < 0? -1 : 1
        sum += abs(i)
    }
    return prod * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

prod *= i < 0? -1 : 1 // expected expression

prod *= i < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

prod *= i < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

prod *= i < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

prod *= i < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

prod *= i < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

prod *= i < 0? -1 : 1 // integer literal is unused

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var result = 1
    var sign = 1
    for i in 0..<arr.count {
        result *= sign
        sign = arr[i] > 0? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var result = 1
    var sign = 1
    for i in 0..<arr.count {
        result *= sign
        sign = arr[i] > 0? 1 : -1
    }
    return result
}
```

sign = arr[i] > 0? 1 : -1 // expected expression

sign = arr[i] > 0? 1 : -1 // cannot assign value of type 'Bool' to type 'Int'

sign = arr[i] > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

sign = arr[i] > 0? 1 : -1 // integer literal is unused

sign = arr[i] > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

sign = arr[i] > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

sign = arr[i] > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            prod = 0
        } else if i > 0 {
            prod *= 1
        } else {
            prod *= -1
        }
        sum += abs(i)
    }
    return prod * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            prod = 0
        } else if i > 0 {
            prod *= 1
        } else {
            prod *= -1
        }
        sum += abs(i)
    }
    return prod * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            prod *= 0
        } else if i > 0 {
            prod *= 1
        } else {
            prod *= -1
        }
        sum += abs(i)
    }
    return prod * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            prod *= 0
        } else if i > 0 {
            prod *= 1
        } else {
            prod *= -1
        }
        sum += abs(i)
    }
    return prod * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var prod = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            prod *= 0
        } else if num > 0 {
            prod *= 1
        } else {
            prod *= -1
        }
        sum += abs(num)
    }
    return prod * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var prod = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            prod *= 0
        } else if num > 0 {
            prod *= 1
        } else {
            prod *= -1
        }
        sum += abs(num)
    }
    return prod * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var result = 1
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            result = 0
            break
        }
        if arr[i] < 0 {
            sign *= -1
        }
    }
    return result * sign
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var result = 1
    var sign = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            result = 0
            break
        }
        if arr[i] < 0 {
            sign *= -1
        }
    }
    return result * sign
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            prod *= 0
        } else if i > 0 {
            prod *= 1
        } else {
            prod *= -1
        }
        sum += abs(i)
    }
    return prod * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var prod = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            prod *= 0
        } else if i > 0 {
            prod *= 1
        } else {
            prod *= -1
        }
        sum += abs(i)
    }
    return prod * sum
}
```

Problem #145 Experiment #127

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    // your code here
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // your code here
}
```

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
  // your code here
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
  // your code here
}
```

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            sum = 0
            break
        }
        if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            sum = 0
            break
        }
        if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            sum = 0
            break
        } else if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for i in arr {
        if i == 0 {
            sum = 0
            break
        } else if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        } else if num > 0 {
            product *= 1
        } else {
            product *= -1
        }
        sum += abs(num)
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        product *= num < 0? -1 : 1
        sum += abs(num)
    }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        product *= num < 0? -1 : 1
        sum += abs(num)
    }
    return product * sum
}
```

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

func prodSigns(arr: [Int]) -> Int? {
    // your code here
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // your code here
}
```

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    return sum * product
}
```

Problem #145 Experiment #128

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    var result = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] < 0 {
            result *= -1
        }
    }
    return arr.map { $0.abs() }.reduce(0, combine: +) * result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    var result = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] < 0 {
            result *= -1
        }
    }
    return arr.map { $0.abs() }.reduce(0, combine: +) * result
}
```

return arr.map { $0.abs() }.reduce(0, combine: +) * result // value of type 'Int' has no member 'abs'

return arr.map { $0.abs() }.reduce(0, combine: +) * result // extraneous argument label 'combine:' in call

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        sum += arr[i].magnitude
        if arr[i] < 0 {
            product *= -1
        }
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        sum += arr[i].magnitude
        if arr[i] < 0 {
            product *= -1
        }
    }
    return sum * product
}
```

sum += arr[i].magnitude // cannot convert value of type 'UInt' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        } else if arr[i] > 0 {
            sum += arr[i]
        } else {
            sum -= arr[i]
        }
        product *= arr[i]
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        } else if arr[i] > 0 {
            sum += arr[i]
        } else {
            sum -= arr[i]
        }
        product *= arr[i]
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        }
    }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            product *= 1
        } else if arr[i] < 0 {
            product *= -1
        }
        sum += abs(arr[i])
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var prod = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            prod = 0
            break
        }
        if arr[i] > 0 {
            prod *= 1
        } else if arr[i] < 0 {
            prod *= -1
        }
        sum += abs(arr[i])
    }
    return sum * prod
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var prod = 1
    for i in 0..<arr.count {
        if arr[i] == 0 {
            prod = 0
            break
        }
        if arr[i] > 0 {
            prod *= 1
        } else if arr[i] < 0 {
            prod *= -1
        }
        sum += abs(arr[i])
    }
    return sum * prod
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            sum += arr[i]
        } else if arr[i] < 0 {
            sum -= arr[i]
        }
        product *= arr[i]
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    for i in 0..<arr.count {
        if arr[i] == 0 {
            return 0
        }
        if arr[i] > 0 {
            sum += arr[i]
        } else if arr[i] < 0 {
            sum -= arr[i]
        }
        product *= arr[i]
    }
    return sum * product
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #129

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = num > 0? 1 : -1
        sum += abs(num) * sign
        product *= sign
    }
    
    return sum * product
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = num > 0? 1 : -1
        sum += abs(num) * sign
        product *= sign
    }
    
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // integer literal is unused

let sign = num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : -1 // expected expression

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = num > 0? 1 : -1
        sum += abs(num) * sign
        product *= sign
    }
    
    return sum * product
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = num > 0? 1 : -1
        sum += abs(num) * sign
        product *= sign
    }
    
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // integer literal is unused

let sign = num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : -1 // expected expression

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : -1
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : -1
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // integer literal is unused

let sign = num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : -1 // expected expression

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for num in arr {
        let sign = num > 0? 1 : (num < 0? -1 : 0)
        signProduct *= sign
        magnitudeSum += abs(num)
    }
    
    return signProduct * magnitudeSum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : (num < 0? -1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : (num < 0? -1 : 0) // integer literal is unused

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : (num < 0? -1 : 0) // expected expression

let sign = num > 0? 1 : (num < 0? -1 : 0) // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = num > 0? 1 : -1
        sum += abs(num) * sign
        product *= sign
    }
    
    return sum * product
}

<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil<|im_end|>
<|im_start|>assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = num > 0? 1 : -1
        sum += abs(num) * sign
        product *= sign
    }
    
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // integer literal is unused

let sign = num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let sign = num > 0? 1 : -1 // expected expression

let sign = num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

let sign = num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

Problem #145 Experiment #130

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let signs = arr.map { $0.sign }
    let magnitudes = arr.map { abs($0) }
    
    let productOfMagnitudes = magnitudes.reduce(1, *)
    let sumOfSigns = signs.reduce(0, +)
    
    return productOfMagnitudes * sumOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let signs = arr.map { $0.sign }
    let magnitudes = arr.map { abs($0) }
    
    let productOfMagnitudes = magnitudes.reduce(1, *)
    let sumOfSigns = signs.reduce(0, +)
    
    return productOfMagnitudes * sumOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))         // Output: 0
print(prodSigns(arr: []))             // Output: nil
```

let signs = arr.map { $0.sign } // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let sumOfMagnitudes = arr.reduce(0) { $0 + abs($1) }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let sumOfMagnitudes = arr.reduce(0) { $0 + abs($1) }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
    
    return sumOfMagnitudes * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))         // Output: 0
print(prodSigns(arr: []))             // Output: nil
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let productOfSigns = arr.reduce(1, { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) })
    let sumOfMagnitudes = arr.reduce(0, { $0 + abs($1) })
    
    return productOfSigns * sumOfMagnitudes
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let productOfSigns = arr.reduce(1, { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) })
    let sumOfMagnitudes = arr.reduce(0, { $0 + abs($1) })
    
    return productOfSigns * sumOfMagnitudes
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))         // Output: 0
print(prodSigns(arr: []))             // Output: nil
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let sumOfMagnitudes = arr.map { abs($0) }.reduce(0, +)
    let productOfSigns = arr.map { $0 == 0 ? 0 : $0 > 0 ? 1 : -1 }.reduce(1, *)
    
    return sumOfMagnitudes * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let sumOfMagnitudes = arr.map { abs($0) }.reduce(0, +)
    let productOfSigns = arr.map { $0 == 0 ? 0 : $0 > 0 ? 1 : -1 }.reduce(1, *)
    
    return sumOfMagnitudes * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))         // Output: 0
print(prodSigns(arr: []))             // Output: nil
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
    let sumOfMagnitudes = arr.reduce(0) { $0 + abs($1) }
    return productOfSigns * sumOfMagnitudes
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
    let sumOfMagnitudes = arr.reduce(0) { $0 + abs($1) }
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    let productOfSigns = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }.reduce(1, *)
    let sumOfMagnitudes = arr.map { abs($0) }.reduce(0, +)
    
    return productOfSigns * sumOfMagnitudes
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    let productOfSigns = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }.reduce(1, *)
    let sumOfMagnitudes = arr.map { abs($0) }.reduce(0, +)
    
    return productOfSigns * sumOfMagnitudes
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))         // Output: 0
print(prodSigns(arr: []))             // Output: nil
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
    
    return magnitudes.reduce(0, +) * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
    
    return magnitudes.reduce(0, +) * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))         // Output: 0
print(prodSigns(arr: []))             // Output: nil
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
    
    return magnitudes.reduce(0, +) * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productOfSigns = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
    
    return magnitudes.reduce(0, +) * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))         // Output: 0
print(prodSigns(arr: []))             // Output: nil
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, *)
    let sumOfMagnitudes = arr.reduce(0) { $0 + abs($1) }
    return product * sumOfMagnitudes
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, *)
    let sumOfMagnitudes = arr.reduce(0) { $0 + abs($1) }
    return product * sumOfMagnitudes
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    let magnitudes = arr.map { abs($0) }
    let productOfSigns = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }.reduce(1, *)
    
    return magnitudes.reduce(0, +) * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    let magnitudes = arr.map { abs($0) }
    let productOfSigns = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }.reduce(1, *)
    
    return magnitudes.reduce(0, +) * productOfSigns
}

// Example usage:
print(prodSigns(arr: [1, 2, 2, -4]))  // Output: 9
print(prodSigns(arr: [0, 1]))         // Output: 0
print(prodSigns(arr: []))             // Output: nil
```

Problem #145 Experiment #131

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    
    let productOfMagnitudes = magnitudes.reduce(1, +)
    let productOfSigns = productsOfSigns.reduce(1, *)
    
    return productOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    
    let productOfMagnitudes = magnitudes.reduce(1, +)
    let productOfSigns = productsOfSigns.reduce(1, *)
    
    return productOfMagnitudes * productOfSigns
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0.signum() }
    
    let productOfMagnitudes = magnitudes.reduce(1, +)
    let productOfSigns = productsOfSigns.reduce(1, *)
    
    return productOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0.signum() }
    
    let productOfMagnitudes = magnitudes.reduce(1, +)
    let productOfSigns = productsOfSigns.reduce(1, *)
    
    return productOfMagnitudes * productOfSigns
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0.signum() }

    let productOfSigns = productsOfSigns.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0.signum() }

    let productOfSigns = productsOfSigns.reduce(1, *)
    let sumOfMagnitudes = magnitudes.reduce(0, +)

    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            productOfSigns *= -1
        }
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            productOfSigns *= -1
        }
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

Problem #145 Experiment #132

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1 }
    let sign = product > 0 ? 1 : (product < 0 ? -1 : 0)
    return abs(product) * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1 }
    let sign = product > 0 ? 1 : (product < 0 ? -1 : 0)
    return abs(product) * sign
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for num in arr {
        if num == 0 {
            return 0
        }
        sign *= num > 0 ? 1 : -1
        result *= abs(num)
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    var result = 1
    var sign = 1
    for num in arr {
        if num == 0 {
            return 0
        }
        sign *= num > 0 ? 1 : -1
        result *= abs(num)
    }
    return result * sign
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let product = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let product = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let magnitudes = arr.map { abs($0) }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let productOfMagnitudes = magnitudes.reduce(1, *)
    let productOfSigns = signs.reduce(1, *)
    return productOfMagnitudes * productOfSigns
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let magnitudes = arr.map { abs($0) }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let productOfMagnitudes = magnitudes.reduce(1, *)
    let productOfSigns = signs.reduce(1, *)
    return productOfMagnitudes * productOfSigns
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let product = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let product = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.signum()
        sum += abs(num)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.signum()
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let sign = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
    let magnitude = arr.reduce(0) { $0 + abs($1) }
    return sign * magnitude
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let sign = arr.reduce(1) { $0 * ($1 > 0 ? 1 : $1 < 0 ? -1 : 0) }
    let magnitude = arr.reduce(0) { $0 + abs($1) }
    return sign * magnitude
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let product = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    let product = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, { $0 * $1 })
    let sign = product > 0 ? 1 : (product < 0 ? -1 : 0)
    return abs(product) * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, { $0 * $1 })
    let sign = product > 0 ? 1 : (product < 0 ? -1 : 0)
    return abs(product) * sign
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #133

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

Problem #145 Experiment #134

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= n
        default:
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= n
        default:
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= n
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return product * sum
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        switch num {
        case 0:
            return 0
        case let n where n > 0:
            product *= n
        case let n where n < 0:
            product *= -1
        default:
            break
        }
        sum += abs(num)
    }
    return product * sum
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // cannot use optional chaining on non-optional value of type 'Int'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // cannot use optional chaining on non-optional value of type 'Int'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // cannot use optional chaining on non-optional value of type 'Int'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // cannot use optional chaining on non-optional value of type 'Int'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // cannot use optional chaining on non-optional value of type 'Int'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // cannot use optional chaining on non-optional value of type 'Int'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // expected expression

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}

Question:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil

Answer:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 == 0? 0 : $0 / abs($0) }
    let magnitudes = arr.map { abs($0) }
    return magnitudes.reduce(1, *) * signs.reduce(1, *)
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // cannot use optional chaining on non-optional value of type 'Int'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 == 0? 0 : $0 / abs($0) } // expected expression

Problem #145 Experiment #135

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    
    return product * sum
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    
    return product * sum
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    
    return product * sum
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    
    return product * sum
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    
    return product * sum
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            return 0
        }
    }
    
    return sum * product
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            return 0
        }
    }
    
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num < 0 {
            product *= -1
        } else if num == 0 {
            return 0
        }
        sum += abs(num)
    }
    
    return product * sum
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num < 0 {
            product *= -1
        } else if num == 0 {
            return 0
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num < 0 {
            product *= -1
        } else if num == 0 {
            return 0
        }
        sum += abs(num)
    }
    
    return product * sum
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num < 0 {
            product *= -1
        } else if num == 0 {
            return 0
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num < 0 {
            product *= -1
        } else if num == 0 {
            return 0
        }
        sum += abs(num)
    }
    
    return product * sum
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num < 0 {
            product *= -1
        } else if num == 0 {
            return 0
        }
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num < 0 {
            productOfSigns *= -1
        } else if num == 0 {
            return 0
        }
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

You are an AI programming assistant, utilizing the Deepseek Coder model, developed by Deepseek Company, and you only answer questions related to computer science. For politically sensitive questions, security and privacy issues, and other non-computer science questions, you will refuse to answer
### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num < 0 {
            productOfSigns *= -1
        } else if num == 0 {
            return 0
        }
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

Problem #145 Experiment #136

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

[INST]  Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil[/INST]  ```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
        sum += abs(num)
    }

    return sum * product
}

[INST]  Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil[/INST]  ```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += -num
        }
    }

    return sum * product
}

[INST]  Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil[/INST]  ```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += -num
        }
    }

    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }

        sum += abs(num)
    }

    return product * sum
}

[INST]  Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil[/INST]  ```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }

        sum += abs(num)
    }

    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

[INST]  Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil[/INST]  ```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}

[INST]  Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil[/INST]  ```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
        sum += abs(num)
    }

    return sum * product
}

[INST]  Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil[/INST]  ```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
        sum += abs(num)
    }

    return sum * product
}

[INST]  Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil[/INST]  ```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
        sum += abs(num)
    }

    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += -num
        }
    }

    return product * sum
}

[INST]  Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil[/INST]  ```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += -num
        }
    }

    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return product * sum
}

[INST]  Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil[/INST]  ```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var product = 1
    var sum = 0

    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        }
        sum += abs(num)
    }

    return product * sum
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #137

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= num > 0 ? 1 : -1
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= num > 0 ? 1 : -1
        sumOfMagnitudes += abs(num)
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0.signum() }

    let productOfMagnitudes = magnitudes.reduce(1, *)
    let productOfSigns = productsOfSigns.reduce(1, *)

    return productOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0.signum() }

    let productOfMagnitudes = magnitudes.reduce(1, *)
    let productOfSigns = productsOfSigns.reduce(1, *)

    return productOfMagnitudes * productOfSigns
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    var sumOfMagnitudes = 0
    var productOfSigns = 1

    for num in arr {
        sumOfMagnitudes += abs(num)
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }

    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    var sumOfMagnitudes = 0
    var productOfSigns = 1

    for num in arr {
        sumOfMagnitudes += abs(num)
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }

    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    var sumOfMagnitudes = 0
    var productOfSigns = 1

    for num in arr {
        sumOfMagnitudes += abs(num)
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }

    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }

    var sumOfMagnitudes = 0
    var productOfSigns = 1

    for num in arr {
        sumOfMagnitudes += abs(num)
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }

    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0.signum() }
    
    let productOfMagnitudes = magnitudes.reduce(1, *)
    let productOfSigns = productsOfSigns.reduce(1, *)
    
    return productOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0.signum() }
    
    let productOfMagnitudes = magnitudes.reduce(1, *)
    let productOfSigns = productsOfSigns.reduce(1, *)
    
    return productOfMagnitudes * productOfSigns
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        sumOfMagnitudes += abs(num)
        
        if num == 0 {
            productOfSigns = 0
            break
        } else if num < 0 {
            productOfSigns *= -1
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    
    let productOfMagnitudes = magnitudes.reduce(1, +)
    let productOfSigns = productsOfSigns.reduce(1, *)
    
    return productOfMagnitudes * productOfSigns
}

system
You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let magnitudes = arr.map { abs($0) }
    let productsOfSigns = arr.map { $0 > 0 ? 1 : $0 < 0 ? -1 : 0 }
    
    let productOfMagnitudes = magnitudes.reduce(1, +)
    let productOfSigns = productsOfSigns.reduce(1, *)
    
    return productOfMagnitudes * productOfSigns
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #138

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num == 0 {
            product = 0
            break
        } else if num < 0 {
            product *= -1
        }
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num == 0 {
            product = 0
            break
        } else if num < 0 {
            product *= -1
        }
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let sign = arr.reduce(1) { (result, number) -> Int in
        if number == 0 {
            return 0
        } else if number < 0 {
            return result * -1
        } else {
            return result
        }
    }
    let sum = arr.reduce(0) { (result, number) -> Int in
        if number == 0 {
            return result
        } else {
            return result + abs(number)
        }
    }
    return sign * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let sign = arr.reduce(1) { (result, number) -> Int in
        if number == 0 {
            return 0
        } else if number < 0 {
            return result * -1
        } else {
            return result
        }
    }
    let sum = arr.reduce(0) { (result, number) -> Int in
        if number == 0 {
            return result
        } else {
            return result + abs(number)
        }
    }
    return sign * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num == 0 {
            product = 0
            break
        }
        product *= num > 0 ? 1 : -1
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num == 0 {
            product = 0
            break
        }
        product *= num > 0 ? 1 : -1
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        sum += abs(num)
        if num < 0 {
            product *= -1
        }
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            return 0
        }
        sum += abs(num)
        if num < 0 {
            product *= -1
        }
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    let product = arr.reduce(1) { $0 * $1 }
    return arr.reduce(0) { $0 + abs($1) } * product.signum()
}

extension BinaryInteger {
    func signum() -> Int {
        return self < 0 ? -1 : (self > 0 ? 1 : 0)
    }
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    let product = arr.reduce(1) { $0 * $1 }
    return arr.reduce(0) { $0 + abs($1) } * product.signum()
}

extension BinaryInteger {
    func signum() -> Int {
        return self < 0 ? -1 : (self > 0 ? 1 : 0)
    }
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
            break
        }
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
            break
        }
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 0 : num > 0 ? 1 : -1
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num == 0 ? 0 : num > 0 ? 1 : -1
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num == 0 {
            product = 0
        } else if num < 0 {
            product *= -1
        }
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num == 0 {
            product = 0
        } else if num < 0 {
            product *= -1
        }
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num == 0 {
            product = 0
        } else if num < 0 {
            product *= -1
        }
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num == 0 {
            product = 0
        } else if num < 0 {
            product *= -1
        }
    }
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num == 0 {
            product = 0
            break
        }
        product *= num > 0 ? 1 : -1
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num == 0 {
            product = 0
            break
        }
        product *= num > 0 ? 1 : -1
    }
    return sum * product
}
```

Problem #145 Experiment #139

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

Here is the Swift code for the given problem:

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        } else {
            product *= 0
        }
    }
    
    return sum * product
}

Here is the Swift code for the given problem:

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        } else {
            product *= 0
        }
    }
    
    return sum * product
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

Here is the Swift code for the problem:

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

Here is the Swift code for the given problem:

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

Here is the Swift code for the problem:

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = (num > 0) ? 1 : ((num < 0) ? -1 : 0)
        sum += abs(num)
        product *= sign
    }
    
    return sum * product
}

Here is the Swift code for the given problem:

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = (num > 0) ? 1 : ((num < 0) ? -1 : 0)
        sum += abs(num)
        product *= sign
    }
    
    return sum * product
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = (num > 0) ? 1 : (num < 0) ? -1 : 0
        product *= sign
        sum += abs(num)
    }
    
    return sum * product
}

Here is the Swift code for the problem:

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = (num > 0) ? 1 : (num < 0) ? -1 : 0
        product *= sign
        sum += abs(num)
    }
    
    return sum * product
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

Here is the Swift code for the problem:

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

Here is the Swift code for the problem:

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num == 0 {
            product = 0
        }
    }
    
    return sum * product
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = (num > 0) ? 1 : (num < 0) ? -1 : 0
        product *= sign
        sum += abs(num)
    }
    
    return sum * product
}

Here is the Swift code for the given problem:

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        let sign = (num > 0) ? 1 : (num < 0) ? -1 : 0
        product *= sign
        sum += abs(num)
    }
    
    return sum * product
}

Problem #145 Experiment #140

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var signProduct = 1
    var magnitudeSum = 0

    for number in arr {
        if number == 0 {
            return 0
        }
        signProduct *= number > 0 ? 1 : -1
        magnitudeSum += abs(number)
    }

    return magnitudeSum * signProduct
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var signProduct = 1
    var magnitudeSum = 0

    for number in arr {
        if number == 0 {
            return 0
        }
        signProduct *= number > 0 ? 1 : -1
        magnitudeSum += abs(number)
    }

    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }
    
    return magnitudeSum * signProduct
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }
    
    return magnitudeSum * signProduct
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }
    
    return magnitudeSum * signProduct
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }

    var signProduct = 1
    var magnitudeSum = 0

    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }

    return magnitudeSum * signProduct
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }

    var signProduct = 1
    var magnitudeSum = 0

    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }

    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var signProduct = 1
    var magnitudeSum = 0

    for num in arr {
        if num == 0 {
            return 0
        }
        signProduct *= num > 0 ? 1 : -1
        magnitudeSum += abs(num)
    }

    return magnitudeSum * signProduct
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }

    var signProduct = 1
    var magnitudeSum = 0

    for num in arr {
        if num == 0 {
            return 0
        }
        signProduct *= num > 0 ? 1 : -1
        magnitudeSum += abs(num)
    }

    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }

    var signProduct = 1
    var magnitudeSum = 0

    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }

    return magnitudeSum * signProduct
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }

    var signProduct = 1
    var magnitudeSum = 0

    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }

    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }
    
    return magnitudeSum * signProduct
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        if number == 0 {
            return 0
        }
        signProduct *= number > 0 ? 1 : -1
        magnitudeSum += abs(number)
    }
    
    return magnitudeSum * signProduct
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        if number == 0 {
            return 0
        }
        signProduct *= number > 0 ? 1 : -1
        magnitudeSum += abs(number)
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }
    
    return magnitudeSum * signProduct
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var signProduct = 1
    var magnitudeSum = 0
    
    for number in arr {
        magnitudeSum += abs(number)
        if number == 0 {
            signProduct = 0
            break
        } else if number < 0 {
            signProduct *= -1
        }
    }
    
    return magnitudeSum * signProduct
}
```

Problem #145 Experiment #141

func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to store the sum of magnitudes and product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sumOfMagnitudes
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to productOfSigns
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of sumOfMagnitudes and productOfSigns
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to store the sum of magnitudes and product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sumOfMagnitudes
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to productOfSigns
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of sumOfMagnitudes and productOfSigns
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables for the sum of magnitudes and product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the sum of magnitudes multiplied by the product of signs
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables for the sum of magnitudes and product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the sum of magnitudes multiplied by the product of signs
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to store the sum of magnitudes and the product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to store the sum of magnitudes and the product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to hold the sum of magnitudes and the product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of signs multiplied by the sum of magnitudes
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to hold the sum of magnitudes and the product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of signs multiplied by the sum of magnitudes
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to store the sum of magnitudes and the product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude of the current number to the sum
        sumOfMagnitudes += abs(num)
        
        // Multiply the product of signs by the sign of the current number
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to store the sum of magnitudes and the product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude of the current number to the sum
        sumOfMagnitudes += abs(num)
        
        // Multiply the product of signs by the sign of the current number
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables for the sum of magnitudes and product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables for the sum of magnitudes and product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to store the sum of magnitudes and the product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum of magnitudes
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to store the sum of magnitudes and the product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum of magnitudes
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables for the sum of magnitudes and product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Multiply the product of signs by the sign of the number
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the sum of magnitudes multiplied by the product of signs
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables for the sum of magnitudes and product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Multiply the product of signs by the sign of the number
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the sum of magnitudes multiplied by the product of signs
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables for the sum of magnitudes and product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables for the sum of magnitudes and product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Determine the sign of the number and multiply it to the product of signs
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to store the sum of magnitudes and the product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Multiply the product of signs by the sign of the number
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    // Check if the array is empty
    if arr.isEmpty {
        return nil
    }
    
    // Initialize variables to store the sum of magnitudes and the product of signs
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    // Iterate through each element in the array
    for num in arr {
        // Add the magnitude (absolute value) of the number to the sum
        sumOfMagnitudes += abs(num)
        
        // Multiply the product of signs by the sign of the number
        if num > 0 {
            productOfSigns *= 1
        } else if num < 0 {
            productOfSigns *= -1
        } else {
            productOfSigns *= 0
        }
    }
    
    // Return the product of the sum of magnitudes and the product of signs
    return sumOfMagnitudes * productOfSigns
}
```

Problem #145 Experiment #142

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sumOfMagnitudes = 0
    var productOfSigns = 1
    
    for number in arr {
        if number > 0 {
            sumOfMagnitudes += number
        } else if number < 0 {
            sumOfMagnitudes += -number
            productOfSigns *= -1
        } else {
            productOfSigns = 0
        }
    }
    
    return sumOfMagnitudes * productOfSigns
}
```

Problem #145 Experiment #143

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += abs(num)
        }
    }
    
    return product * sum
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += abs(num)
        }
    }
    
    return product * sum
}

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += abs(num)
        }
    }
    
    return product * sum
}

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
            sum += num
        } else if num < 0 {
            product *= -1
            sum += abs(num)
        }
    }
    
    return product * sum
}

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}

```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var sum = 0
    
    for num in arr {
        if num > 0 {
            product *= 1
        } else if num < 0 {
            product *= -1
        } else {
            product *= 0
        }
        
        sum += abs(num)
    }
    
    return product * sum
}
```

Problem #145 Experiment #144

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num > 0 ? 1 : -1
    }
    return result * arr.reduce(1, *)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num > 0 ? 1 : -1
    }
    return result * arr.reduce(1, *)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for number in arr {
        result *= number > 0 ? 1 : -1
    }
    return result * arr.reduce(1, *)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for number in arr {
        result *= number > 0 ? 1 : -1
    }
    return result * arr.reduce(1, *)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num > 0 ? 1 : -1
    }
    return result * arr.reduce(1, *)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num > 0 ? 1 : -1
    }
    return result * arr.reduce(1, *)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for number in arr {
        result *= number > 0 ? 1 : -1
    }
    return arr.reduce(0, { $0 + abs($1 * result) })
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for number in arr {
        result *= number > 0 ? 1 : -1
    }
    return arr.reduce(0, { $0 + abs($1 * result) })
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num > 0 ? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num > 0 ? 1 : -1
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result * arr.reduce(1, *)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result * arr.reduce(1, *)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    for num in arr {
        if num == 0 {
            sum += 0
        } else if num > 0 {
            sum += 1
        } else {
            sum += -1
        }
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    for num in arr {
        if num == 0 {
            sum += 0
        } else if num > 0 {
            sum += 1
        } else {
            sum += -1
        }
    }
    return sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    for num in arr {
        if num == 0 {
            sum += 0
        } else if num > 0 {
            sum += 1
        } else {
            sum -= 1
        }
    }
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    for num in arr {
        if num == 0 {
            sum += 0
        } else if num > 0 {
            sum += 1
        } else {
            sum -= 1
        }
    }
    return sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num > 0 ? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        if num == 0 {
            result = 0
            break
        }
        result *= num > 0 ? 1 : -1
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for number in arr {
        if number == 0 {
            result = 0
            break
        }
        result *= number > 0 ? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for number in arr {
        if number == 0 {
            result = 0
            break
        }
        result *= number > 0 ? 1 : -1
    }
    return result
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #146

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let signsProduct = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let magnitudesSum = magnitudes.reduce(0, +)
    return magnitudesSum * signsProduct
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let signsProduct = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let magnitudesSum = magnitudes.reduce(0, +)
    return magnitudesSum * signsProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var prod = 1
    for num in arr {
        if num == 0 {
            prod *= 1
        } else if num > 0 {
            prod *= 1
            sum += num
        } else {
            prod *= -1
            sum -= num
        }
    }
    return sum * prod
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var prod = 1
    for num in arr {
        if num == 0 {
            prod *= 1
        } else if num > 0 {
            prod *= 1
            sum += num
        } else {
            prod *= -1
            sum -= num
        }
    }
    return sum * prod
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let signsProduct = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let magnitudesSum = magnitudes.reduce(0, +)
    return magnitudesSum * signsProduct
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let signsProduct = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let magnitudesSum = magnitudes.reduce(0, +)
    return magnitudesSum * signsProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var prod = 1
    for num in arr {
        if num == 0 {
            prod *= 1
        } else if num > 0 {
            prod *= 1
            sum += num
        } else {
            prod *= -1
            sum -= num
        }
    }
    return sum * prod
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var prod = 1
    for num in arr {
        if num == 0 {
            prod *= 1
        } else if num > 0 {
            prod *= 1
            sum += num
        } else {
            prod *= -1
            sum -= num
        }
    }
    return sum * prod
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let signsProduct = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let magnitudesSum = magnitudes.reduce(0, +)
    return magnitudesSum * signsProduct
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let signsProduct = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let magnitudesSum = magnitudes.reduce(0, +)
    return magnitudesSum * signsProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let signsProduct = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let magnitudesSum = magnitudes.reduce(0, +)
    return magnitudesSum * signsProduct
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let signsProduct = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let magnitudesSum = magnitudes.reduce(0, +)
    return magnitudesSum * signsProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var prod = 1
    for num in arr {
        if num == 0 {
            prod *= 1
        } else if num > 0 {
            prod *= 1
            sum += num
        } else {
            prod *= -1
            sum -= num
        }
    }
    return sum * prod
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var prod = 1
    for num in arr {
        if num == 0 {
            prod *= 1
        } else if num > 0 {
            prod *= 1
            sum += num
        } else {
            prod *= -1
            sum -= num
        }
    }
    return sum * prod
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var prod = 1
    for i in arr {
        if i == 0 {
            prod *= 1
        } else if i > 0 {
            prod *= -1
        } else {
            prod *= 1
        }
        sum += abs(i) * prod
    }
    return sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var prod = 1
    for i in arr {
        if i == 0 {
            prod *= 1
        } else if i > 0 {
            prod *= -1
        } else {
            prod *= 1
        }
        sum += abs(i) * prod
    }
    return sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var prod = 1
    for i in arr {
        if i == 0 {
            prod *= 1
        } else if i > 0 {
            prod *= -1
        } else {
            prod *= 1
        }
        sum += abs(i) * prod
    }
    return sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else { return nil }
    var sum = 0
    var prod = 1
    for i in arr {
        if i == 0 {
            prod *= 1
        } else if i > 0 {
            prod *= -1
        } else {
            prod *= 1
        }
        sum += abs(i) * prod
    }
    return sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let signsProduct = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let magnitudesSum = magnitudes.reduce(0, +)
    return magnitudesSum * signsProduct
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : $0 > 0 ? 1 : 0 }
    let signsProduct = signs.reduce(1, *)
    let magnitudes = arr.map { abs($0) }
    let magnitudesSum = magnitudes.reduce(0, +)
    return magnitudesSum * signsProduct
}
```

Problem #145 Experiment #150

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num.sign
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num.sign
    }
    return sum * product
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num.sign
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num.sign
    }
    return sum * product
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num.sign
        sum += abs(num)
    }
    return product * sum
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num.sign
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num.sign
    }
    return sum * product
}
```

product *= num.sign // value of type 'Int' has no member 'sign'

Problem #145 Experiment #151

func prodSigns(arr: [Int]) -> Int? {
    // write your code here
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // write your code here
}

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
    // write your code here
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // write your code here
}

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
    // write your code here
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // write your code here
}

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
    // write your code here
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // write your code here
}

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
    // write your code here
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // write your code here
}

} // missing return in global function expected to return 'Int?'

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

func prodSigns(arr: [Int]) -> Int? {
    return nil
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    return nil
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    return nil
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    return nil
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #153

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

Problem #145 Experiment #155

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.

XCTAssertTrue(prodSigns(arr: [1, 2, 2, -4]) == -9) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [0, 1]) == 0) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [1, 1, 1, 2, 3, -1, 1]) == -10) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [] as [Int]) == nil) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [2, 4, 1, 2, -1, -1, 9]) == 20) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, -1, 1]) == 4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 1]) == -4) // cannot find 'prodSigns' in scope

XCTAssertTrue(prodSigns(arr: [-1, 1, 1, 0]) == 0) // cannot find 'prodSigns' in scope

Problem #145 Experiment #157

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for num in arr {
        if num > 0 {
            result *= 1
        } else if num < 0 {
            result *= -1
        } else {
            result *= 0
        }
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for num in arr {
        if num > 0 {
            result *= 1
        } else if num < 0 {
            result *= -1
        } else {
            result *= 0
        }
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var signs = [Int]()
    for num in arr {
        if num > 0 {
            signs.append(1)
        } else if num < 0 {
            signs.append(-1)
        } else {
            signs.append(0)
        }
    }
    var result = 1
    for sign in signs {
        result *= sign
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var signs = [Int]()
    for num in arr {
        if num > 0 {
            signs.append(1)
        } else if num < 0 {
            signs.append(-1)
        } else {
            signs.append(0)
        }
    }
    var result = 1
    for sign in signs {
        result *= sign
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result * arr.reduce(1, { $0 * $1 })
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result * arr.reduce(1, { $0 * $1 })
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var res = 1
    for num in arr {
        if num < 0 {
            res *= -1
        }
    }
    return res * arr.reduce(1, { $0 * $1 })
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var res = 1
    for num in arr {
        if num < 0 {
            res *= -1
        }
    }
    return res * arr.reduce(1, { $0 * $1 })
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    for num in arr {
        result *= numSign(num)
    }
    return result
}

func numSign(_ num: Int) -> Int {
    return num > 0 ? 1 : (num < 0 ? -1 : 0)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    for num in arr {
        result *= numSign(num)
    }
    return result
}

func numSign(_ num: Int) -> Int {
    return num > 0 ? 1 : (num < 0 ? -1 : 0)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var result = 1
    for num in arr {
        if num == 0 {
            return nil
        }
        result *= num > 0 ? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var result = 1
    for num in arr {
        if num == 0 {
            return nil
        }
        result *= num > 0 ? 1 : -1
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    var signs = [Int]()
    for i in 0..<arr.count {
        signs.append(arr[i] > 0 ? 1 : (arr[i] < 0 ? -1 : 0))
    }
    var result = 1
    for i in 0..<signs.count {
        result *= signs[i]
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    var signs = [Int]()
    for i in 0..<arr.count {
        signs.append(arr[i] > 0 ? 1 : (arr[i] < 0 ? -1 : 0))
    }
    var result = 1
    for i in 0..<signs.count {
        result *= signs[i]
    }
    return result
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #160

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
    }
    return sum * product
}
`````````swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        }
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : ($0 > 0 ? 1 : 0) }
    let sum = arr.map { abs($0) }.reduce(0, +)
    return sum * signs.reduce(1, *)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : ($0 > 0 ? 1 : 0) }
    let sum = arr.map { abs($0) }.reduce(0, +)
    return sum * signs.reduce(1, *)
}
`````````swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 < 0 ? -1 : ($0 > 0 ? 1 : 0) }
    let sum = arr.map { abs($0) }.reduce(0, +)
    return sum * signs.reduce(1, *)
}

prodSigns(arr: [1, 2, 2, -4]) // 9
prodSigns(arr: [0, 1]) // 0
prodSigns(arr: [] as [Int]) // nil
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num >= 0 ? 1 : -1
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num >= 0 ? 1 : -1
    }
    return sum * product
}
`````````swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num >= 0 ? 1 : -1
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num >= 0 ? 1 : -1
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num >= 0 ? 1 : -1
    }
    return sum * product
}
`````````swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num >= 0 ? 1 : -1
    }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num >= 0 ? 1 : -1
    }
    
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        product *= num >= 0 ? 1 : -1
    }
    
    return sum * product
}
`````````swift
// Test cases
print(prodSigns(arr: [1, 2, 2, -4])) // Output: 9
print(prodSigns(arr: [0, 1])) // Output: 0
print(prodSigns(arr: [] as [Int])) // Output: nil
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    
    let sumOfMagnitudes = magnitudes.reduce(0, +)
    let productOfSigns = signs.reduce(1, *)
    
    return sumOfMagnitudes * productOfSigns
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    
    let sumOfMagnitudes = magnitudes.reduce(0, +)
    let productOfSigns = signs.reduce(1, *)
    
    return sumOfMagnitudes * productOfSigns
}
``````
```swift
// Test cases
print(prodSigns(arr: [1, 2, 2, -4])) // 9
print(prodSigns(arr: [0, 1])) // 0
print(prodSigns(arr: [] as [Int])) // nil
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    let product = signs.reduce(1, *)
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    let product = signs.reduce(1, *)
    return sum * product
}
`````````swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let signs = arr.map { $0 >= 0 ? 1 : -1 }
    let magnitudes = arr.map { abs($0) }
    let sum = magnitudes.reduce(0, +)
    let product = signs.reduce(1, *)
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0 ? 1 : -1
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0 ? 1 : -1
    }
    return sum * product
}
`````````swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0 ? 1 : -1
    }
    return sum * product
}

prodSigns(arr: [1, 2, 2, -4])
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0 ? 1 : -1
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0 ? 1 : -1
    }
    return sum * product
}
``````
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num > 0 ? 1 : -1
    }
    return sum * product
}

prodSigns(arr: [1, 2, 2, -4])
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        } else {
            return 0
        }
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        } else {
            return 0
        }
    }
    return sum * product
}
`````````swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        if num < 0 {
            product *= -1
        } else if num > 0 {
            product *= 1
        } else {
            return 0
        }
    }
    return sum * product
}
```

Problem #145 Experiment #162

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for num in arr {
        if num == 0 {
            return nil
        }
        result *= num > 0 ? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for num in arr {
        if num == 0 {
            return nil
        }
        result *= num > 0 ? 1 : -1
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= numSign(num)
    }
    return result
}

func numSign(_ num: Int) -> Int {
    return num > 0 ? 1 : (num < 0 ? -1 : 0)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= numSign(num)
    }
    return result
}

func numSign(_ num: Int) -> Int {
    return num > 0 ? 1 : (num < 0 ? -1 : 0)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for num in arr {
        result *= numSign(num)
    }
    return result
}

func numSign(num: Int) -> Int {
    if num > 0 {
        return 1
    } else if num < 0 {
        return -1
    } else {
        return 0
    }
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for num in arr {
        result *= numSign(num)
    }
    return result
}

func numSign(num: Int) -> Int {
    if num > 0 {
        return 1
    } else if num < 0 {
        return -1
    } else {
        return 0
    }
}
```

result *= numSign(num) // missing argument label 'num:' in call

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    for i in 0..<arr.count {
        result *= arr[i] > 0 ? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    for i in 0..<arr.count {
        result *= arr[i] > 0 ? 1 : -1
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    for num in arr {
        if num == 0 {
            return 0
        }
        if num > 0 {
            signs.append(1)
        } else {
            signs.append(-1)
        }
    }
    var res = 1
    for sign in signs {
        res *= sign
    }
    return res
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var signs = [Int]()
    for num in arr {
        if num == 0 {
            return 0
        }
        if num > 0 {
            signs.append(1)
        } else {
            signs.append(-1)
        }
    }
    var res = 1
    for sign in signs {
        res *= sign
    }
    return res
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var result = 1
    for num in arr {
        result *= num > 0 ? 1 : -1
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    var sign = 1
    for num in arr {
        if num == 0 {
            return nil
        }
        sign = (num > 0) ? 1 : -1
        result *= sign
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else {
        return nil
    }
    var result = 1
    var sign = 1
    for num in arr {
        if num == 0 {
            return nil
        }
        sign = (num > 0) ? 1 : -1
        result *= sign
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sign = 1
    var res = 1
    for num in arr {
        if num == 0 {
            return nil
        }
        sign = (sign * num) / abs(num)
        res *= sign
    }
    return res
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard arr.count > 0 else {
        return nil
    }
    var sign = 1
    var res = 1
    for num in arr {
        if num == 0 {
            return nil
        }
        sign = (sign * num) / abs(num)
        res *= sign
    }
    return res
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for i in 0..<arr.count {
        if arr[i] > 0 {
            result *= 1
        } else if arr[i] < 0 {
            result *= -1
        } else {
            result *= 0
        }
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for i in 0..<arr.count {
        if arr[i] > 0 {
            result *= 1
        } else if arr[i] < 0 {
            result *= -1
        } else {
            result *= 0
        }
    }
    return result
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for num in arr {
        result *= numSign(num: num)
    }
    return result
}

func numSign(num: Int) -> Int {
    if num > 0 {
        return 1
    } else if num < 0 {
        return -1
    } else {
        return 0
    }
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    var result = 1
    for num in arr {
        result *= numSign(num: num)
    }
    return result
}

func numSign(num: Int) -> Int {
    if num > 0 {
        return 1
    } else if num < 0 {
        return -1
    } else {
        return 0
    }
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #164

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 0
    var negative = 0
    for num in arr {
        if num > 0 {
            positive += 1
        } else if num < 0 {
            negative += 1
        }
    }
    return positive * negative * arr.reduce(1, *)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 0
    var negative = 0
    for num in arr {
        if num > 0 {
            positive += 1
        } else if num < 0 {
            negative += 1
        }
    }
    return positive * negative * arr.reduce(1, *)
}

// Tests
assert(prodSigns(arr: [1, 2, 2, -4]) == 9)
assert(prodSigns(arr: [0, 1]) == 0)
assert(prodSigns(arr: []) == nil)
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 1
    var negative = 1
    var zero = 1
    for num in arr {
        if num > 0 {
            positive *= num
        } else if num < 0 {
            negative *= num
        } else {
            zero *= 0
        }
    }
    return positive * negative * zero
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 1
    var negative = 1
    var zero = 1
    for num in arr {
        if num > 0 {
            positive *= num
        } else if num < 0 {
            negative *= num
        } else {
            zero *= 0
        }
    }
    return positive * negative * zero
}

// Tests
print(prodSigns(arr: [1, 2, 2, -4])!)
print(prodSigns(arr: [0, 1])!)
print(prodSigns(arr: []) == nil)
print(prodSigns(arr: [-1, 2, 3, 0, 5])!)
print(prodSigns(arr: [1, 2, 3, 0, -5])!)
print(prodSigns(arr: [1, 2, 3, 0, 5, -10]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, -10, 10]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1, 2]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1, 2, 3]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1, 2, 3, 4]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1, 2, 3, 4, 5]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1, 2, 3, 4, 5, 6]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1, 2, 3, 4, 5, 6, 7]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1, 2, 3, 4, 5, 6, 7, 8]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1, 2, 3, 4, 5, 6, 7, 8, 9]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) == nil)
print(prodSigns(arr: [1, 2, 3, 0, 5, 10, -10, 0, 1, -1, 2, 3, 4,

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 0
    var negative = 0
    for num in arr {
        if num > 0 {
            positive += 1
        } else if num < 0 {
            negative += 1
        }
    }
    return positive * negative * arr.reduce(1, *)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 0
    var negative = 0
    for num in arr {
        if num > 0 {
            positive += 1
        } else if num < 0 {
            negative += 1
        }
    }
    return positive * negative * arr.reduce(1, *)
}

// Tests
print(prodSigns(arr: [1, 2, 2, -4])!)
print(prodSigns(arr: [0, 1])!)
print(prodSigns(arr: []) == nil)
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0? 1 : $0 < 0? -1 : 0 }
    let product = signs.reduce(1, *)
    let sum = arr.reduce(0, +) * product
    return sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    let signs = arr.map { $0 > 0? 1 : $0 < 0? -1 : 0 }
    let product = signs.reduce(1, *)
    let sum = arr.reduce(0, +) * product
    return sum
}

// Tests
assert(prodSigns(arr: [1, 2, 2, -4]) == 9)
assert(prodSigns(arr: [0, 1]) == 0)
assert(prodSigns(arr: []) == nil)
assert(prodSigns(arr: [-1, -2, 3, 4, 5]) == -120)
assert(prodSigns(arr: [1, -2, 3, -4, 5]) == 120)
assert(prodSigns(arr: [1, 2, 3, 4, 5]) == 120)
assert(prodSigns(arr: [-1, -2, -3, -4, -5]) == 120)
assert(prodSigns(arr: [-1, -2, 3, 4, -5]) == -120)
assert(prodSigns(arr: [-1, -2, 3, 4, 5]) == -120)
assert(prodSigns(arr: [1, -2, 3, 4, -5]) == -120)
assert(prodSigns(arr: [1, -2, 3, 4, 5]) == 120)
assert(prodSigns(arr: [1, 2, 3, 4, -5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, 5]) == 120)
assert(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) == 3628800)
assert(prodSigns(arr: [-1, -2, -3, -4, -5, -6, -7, -8, -9, -10]) == -3628800)
assert(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, -10]) == -3628800)
assert(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, -9, -10]) == 3628800)
assert(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, -9, 10]) == 3628800)
assert(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) == 3628800)
assert(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]) == 3628800)
assert(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, -20]) == -3628800)
assert(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, -18, -19, -20]) == -3628800)
assert(prodSigns(arr: [1, 2, 3, 4,

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

let signs = arr.map { $0 > 0? 1 : $0 < 0? -1 : 0 } // cannot use optional chaining on non-optional value of type 'Int'

let signs = arr.map { $0 > 0? 1 : $0 < 0? -1 : 0 } // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

let signs = arr.map { $0 > 0? 1 : $0 < 0? -1 : 0 } // consecutive statements on a line must be separated by ';'

let signs = arr.map { $0 > 0? 1 : $0 < 0? -1 : 0 } // expected expression

let signs = arr.map { $0 > 0? 1 : $0 < 0? -1 : 0 } // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var signs = 1
    var product = 1
    for num in arr {
        if num == 0 {
            return 0
        }
        if num < 0 {
            signs *= -1
        }
        product *= num
    }
    return signs * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var signs = 1
    var product = 1
    for num in arr {
        if num == 0 {
            return 0
        }
        if num < 0 {
            signs *= -1
        }
        product *= num
    }
    return signs * product
}

// Tests
print(prodSigns(arr: [1, 2, 2, -4])!)
print(prodSigns(arr: [0, 1])!)
print(prodSigns(arr: []) == nil)
print(prodSigns(arr: [-1, -2, 3, 0, 5])!)
print(prodSigns(arr: [1, 2, 3, 4, 5])!)
print(prodSigns(arr: [1, 2, 3, 4, -5])!)
print(prodSigns(arr: [-1, -2, 3, 4, 5])! == -120)
print(prodSigns(arr: [-1, -2, -3, 4, 5])! == -120)
print(prodSigns(arr: [1, 2, 3, 4, -5])! == 120)
print(prodSigns(arr: [1, 2, 3, 4, 5])! == 120)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])! == 3628800)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, -10])! == -3628800)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, -9, 10])! == -3628800)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, -9, -10])! == 3628800)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20])! == 2100000000000000000)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, -20])! == -2100000000000000000)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, -18, 19, 20])! == -2100000000000000000)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, -17, 18, 19, 20])! == 2100000000000000000)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, -16, 17, 18, 19, 20])! ==

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 1
    var negative = 1
    var zero = 1
    for num in arr {
        if num > 0 {
            positive *= num
        } else if num < 0 {
            negative *= num
        } else {
            zero *= 1
        }
    }
    return positive * negative * zero
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 1
    var negative = 1
    var zero = 1
    for num in arr {
        if num > 0 {
            positive *= num
        } else if num < 0 {
            negative *= num
        } else {
            zero *= 1
        }
    }
    return positive * negative * zero
}

// Tests
print(prodSigns(arr: [1, 2, 2, -4])!)
print(prodSigns(arr: [0, 1])!)
print(prodSigns(arr: []) == nil)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])!)
print(prodSigns(arr: [-1, -2, -3, -4, -5, -6, -7, -8, -9, -10])!)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, -10]) == nil)
print(prodSigns(arr: [-1, -2, -3, -4, -5, -6, -7, -8, -9, 10]) == nil)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]) == nil)
print(prodSigns(arr: [-1, -2, -3, -4, -5, -6, -7, -8, -9, 0]) == nil)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 1]) == nil)
print(prodSigns(arr: [-1, -2, -3, -4, -5, -6, -7, -8, -9, -1]) == nil)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, -1]) == nil)
print(prodSigns(arr: [-1, -2, -3, -4, -5, -6, -7, -8, -9, 1]) == nil)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 1000000000])! > 0)
print(prodSigns(arr: [-1, -2, -3, -4, -5, -6, -7, -8, -9, -1000000000])! < 0)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, -1000000000]) == nil)
print(prodSigns(arr: [-1, -2, -3, -4, -5, -6, -7, -8, -9, 1000000000]) == nil)
print(prodSigns(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 1
    var negative = 1
    var zero = 1
    for num in arr {
        if num > 0 {
            positive *= num
        } else if num < 0 {
            negative *= num
        } else {
            zero *= 0
        }
    }
    return positive * negative * zero
}

func countEqualSigns(arr: [Int]) -> Int {
    var equal = 0
    for i in 1..<arr.count {
        if arr[i - 1] * arr[i] > 0 {
            equal += 1
        }
    }
    return equal
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 1
    var negative = 1
    var zero = 1
    for num in arr {
        if num > 0 {
            positive *= num
        } else if num < 0 {
            negative *= num
        } else {
            zero *= 0
        }
    }
    return positive * negative * zero
}

// You are given an array of integers and you need to return
// the number of subarrays, that have equal signs on both
// their ends.
// Note: subarrays are 1-indexed.
// Example:
// countEqualSigns(arr: [1, -2, 3, 0, 5]) == 2
// countEqualSigns(arr: [1, -2, 3, 0, 5, -2]) == 3
// countEqualSigns(arr: [1, -2, 3, 0, 5, -2, 0]) == 4
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0]) == 3
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0]) == 4
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0, 0]) == 5
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0, 0, 0]) == 6
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0, 0, 0, 0]) == 6
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0, 0, 0, 0, 0]) == 7
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0, 0, 0, 0, 0, 0]) == 7
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0, 0, 0, 0, 0, 0, 0]) == 8
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0]) == 8
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]) == 9
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]) == 9
// countEqualSigns(arr: [1, -2, 3, 0, 5, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]) == 10
func countEqualSigns(arr: [Int]) -> Int {
    var equal = 0
    for i in 1..<arr.count {
        if arr[i - 1] * arr[i] > 0 {
            equal += 1
        }
    }
    return equal
}

// You are given an array of integers and you need to return
// the number of subarrays, that have equal signs on both
// their ends.
// Note: subarrays are 1-indexed.
// Example:
// countEqualSigns2(arr: [1, -2, 3, 0, 5]) == 2
// countEqualSigns2(arr: [1, -2, 3, 0, 5, -2]) == 3
// countEqualSigns2(arr: [1, -2, 3, 0, 5, -2, 0]) ==

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 1
    var negative = 1
    var zero = 1
    for num in arr {
        if num > 0 {
            positive *= num
        } else if num < 0 {
            negative *= num
        } else {
            zero *= 0
        }
    }
    return positive * negative * zero
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 1
    var negative = 1
    var zero = 1
    for num in arr {
        if num > 0 {
            positive *= num
        } else if num < 0 {
            negative *= num
        } else {
            zero *= 0
        }
    }
    return positive * negative * zero
}

// Tests
print(prodSigns(arr: [1, 2, 2, -4])!)
print(prodSigns(arr: [0, 1])!)
print(prodSigns(arr: []) == nil)
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 0
    var negative = 0
    var zero = 0
    for num in arr {
        if num > 0 {
            positive += 1
        } else if num < 0 {
            negative += 1
        } else {
            zero += 1
        }
    }
    let product = positive * negative * zero
    return product == 0? 0 : product * (positive * negative + zero)
}

func countSubarrays(arr: [Int]) -> Int {
    var result = 0
    for i in 0..<arr.count {
        var min = arr[i]
        var max = arr[i]
        for j in i+1..<arr.count {
            min = min < arr[j]? min : arr[j]
            max = max > arr[j]? max : arr[j]
            if max - min <= 1 {
                result += 1
            }
        }
    }
    return result
}

func countSubarraysDiff(arr: [Int]) -> Int {
    var result = 0
    for i in 0..<arr.count {
        var min = arr[i]
        var max = arr[i]
        for j in i+1..<arr.count {
            min = min < arr[j]? min : arr[j]
            max = max > arr[j]? max : arr[j]
            if min!= max {
                result += 1
            }
        }
    }
    return result
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var positive = 0
    var negative = 0
    var zero = 0
    for num in arr {
        if num > 0 {
            positive += 1
        } else if num < 0 {
            negative += 1
        } else {
            zero += 1
        }
    }
    let product = positive * negative * zero
    return product == 0? 0 : product * (positive * negative + zero)
}

// You are given an array of integers. You need to return the
// number of subarrays, in which the absolute difference between
// the maximum and the minimum is less or equal to 1.
// Example:
// countSubarrays(arr: [1, 2, 3, 4, 5]) == 3
// countSubarrays(arr: [1, 3, 5, 7, 9]) == 2
// countSubarrays(arr: [1, 3, 5, 9]) == 1
// countSubarrays(arr: [1, 3, 5, 7, 9, 11]) == 3
// countSubarrays(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) == 10
func countSubarrays(arr: [Int]) -> Int {
    var result = 0
    for i in 0..<arr.count {
        var min = arr[i]
        var max = arr[i]
        for j in i+1..<arr.count {
            min = min < arr[j]? min : arr[j]
            max = max > arr[j]? max : arr[j]
            if max - min <= 1 {
                result += 1
            }
        }
    }
    return result
}

// You are given an array of integers. You need to return the
// number of subarrays, in which the maximum and the minimum are
// not the same.
// Example:
// countSubarraysDiff(arr: [1, 2, 3, 4, 5]) == 3
// countSubarraysDiff(arr: [1, 3, 5, 7, 9]) == 2
// countSubarraysDiff(arr: [1, 3, 5, 9]) == 1
// countSubarraysDiff(arr: [1, 3, 5, 7, 9, 11]) == 3
// countSubarraysDiff(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) == 10
func countSubarraysDiff(arr: [Int]) -> Int {
    var result = 0
    for i in 0..<arr.count {
        var min = arr[i]
        var max = arr[i]
        for j in i+1..<arr.count {
            min = min < arr[j]? min : arr[j]
            max = max > arr[j]? max : arr[j]
            if min!= max {
                result += 1
            }
        }
    }
    return result
}

// You are given an array of integers. You need to return the
// number of subarrays, in which the maximum and the minimum are
// not the same, and the difference between maximum and minimum
// is greater or equal to 5.
// Example:
// countSubarraysDiffMoreThanFive(arr: [1, 2, 3, 4, 5]) == 3
// countSubarraysDiffMoreThanFive(arr: [1, 3, 5, 7, 9]) == 2
// countSubarraysDiffMoreThanFive(arr: [1, 3, 5, 9]) == 1
// countSubarraysDiffMoreThanFive(arr: [1, 3, 5, 7, 9, 11]) == 2
// countSubarraysDiffMoreThanFive(arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) == 3
func countSubarraysDiffMoreThanFive(arr: [Int]) -> Int {
    var result = 0
    for i in 0..<arr.count {
        var min = arr[i]
        var max = arr[i]
        for j in i+1..<arr.count {

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

return product == 0? 0 : product * (positive * negative + zero) // expected expression

return product == 0? 0 : product * (positive * negative + zero) // cannot convert return expression of type 'Bool' to return type 'Int?'

return product == 0? 0 : product * (positive * negative + zero) // integer literal is unused

return product == 0? 0 : product * (positive * negative + zero) // consecutive statements on a line must be separated by ';'

return product == 0? 0 : product * (positive * negative + zero) // consecutive statements on a line must be separated by ';'

return product == 0? 0 : product * (positive * negative + zero) // cannot use optional chaining on non-optional value of type 'Int'

min = min < arr[j]? min : arr[j] // variable is unused

min = min < arr[j]? min : arr[j] // cannot use optional chaining on non-optional value of type 'Int'

min = min < arr[j]? min : arr[j] // expected expression

min = min < arr[j]? min : arr[j] // consecutive statements on a line must be separated by ';'

min = min < arr[j]? min : arr[j] // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

min = min < arr[j]? min : arr[j] // consecutive statements on a line must be separated by ';'

min = min < arr[j]? min : arr[j] // cannot assign value of type 'Bool' to type 'Int'

min = min < arr[j]? min : arr[j] // cannot assign value of type 'Bool' to type 'Int'

min = min < arr[j]? min : arr[j] // expected expression

min = min < arr[j]? min : arr[j] // consecutive statements on a line must be separated by ';'

min = min < arr[j]? min : arr[j] // variable is unused

min = min < arr[j]? min : arr[j] // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

min = min < arr[j]? min : arr[j] // consecutive statements on a line must be separated by ';'

min = min < arr[j]? min : arr[j] // cannot use optional chaining on non-optional value of type 'Int'

if min!= max { // '=' must have consistent whitespace on both sides

if min!= max { // cannot force unwrap value of non-optional type 'Int'

if min!= max { // use of '=' in a boolean context, did you mean '=='?

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var positiveCount = 0
    var negativeCount = 0
    var zeroCount = 0
    for num in arr {
        if num > 0 {
            positiveCount += 1
        } else if num < 0 {
            negativeCount += 1
        } else {
            zeroCount += 1
        }
    }
    if zeroCount > 0 {
        return 0
    }
    let product = positiveCount * negativeCount
    return product * (positiveCount - negativeCount)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var positiveCount = 0
    var negativeCount = 0
    var zeroCount = 0
    for num in arr {
        if num > 0 {
            positiveCount += 1
        } else if num < 0 {
            negativeCount += 1
        } else {
            zeroCount += 1
        }
    }
    if zeroCount > 0 {
        return 0
    }
    let product = positiveCount * negativeCount
    return product * (positiveCount - negativeCount)
}

// Tests
assert(prodSigns(arr: [1, 2, 2, -4]) == 9)
assert(prodSigns(arr: [0, 1]) == 0)
assert(prodSigns(arr: []) == nil)
assert(prodSigns(arr: [-1, -2, 3, 4, 5]) == -120)
assert(prodSigns(arr: [1, -2, 3, 4, -5]) == 120)
assert(prodSigns(arr: [1, 2, 3, 4, 5]) == 0)
assert(prodSigns(arr: [-1, -2, -3, -4, -5]) == 0)
assert(prodSigns(arr: [-1, 2, 3, 4, 5]) == 120)
assert(prodSigns(arr: [1, -2, 3, 4, 5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, -5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, 5]) == 0)
assert(prodSigns(arr: [-1, -2, -3, -4, -5]) == 0)
assert(prodSigns(arr: [-1, 2, 3, 4, 5]) == 120)
assert(prodSigns(arr: [1, -2, 3, 4, 5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, -5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, 5]) == 0)
assert(prodSigns(arr: [-1, -2, -3, -4, -5]) == 0)
assert(prodSigns(arr: [-1, 2, 3, 4, 5]) == 120)
assert(prodSigns(arr: [1, -2, 3, 4, 5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, -5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, 5]) == 0)
assert(prodSigns(arr: [-1, -2, -3, -4, -5]) == 0)
assert(prodSigns(arr: [-1, 2, 3, 4, 5]) == 120)
assert(prodSigns(arr: [1, -2, 3, 4, 5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, -5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, 5]) == 0)
assert(prodSigns(arr: [-1, -2, -3, -4, -5]) == 0)
assert(prodSigns(arr: [-1, 2, 3, 4, 5]) == 120)
assert(prodSigns(arr: [1, -2, 3, 4, 5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, -5]) == -120)
assert(prodSigns(arr: [1, 2, 3, 4, 5]) == 0)
assert(prodSigns(arr: [-1, -2, -3, -4, -5]) ==

 // XCTAssertTrue failed

Problem #145 Experiment #166

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    var result = 1
    var signs = 0
    for element in arr {
        result *= element
        if element > 0 {
            signs += 1
        } else if element < 0 {
            signs -= 1
        }
    }
    return result * signs
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    var result = 1
    var signs = 0
    for element in arr {
        result *= element
        if element > 0 {
            signs += 1
        } else if element < 0 {
            signs -= 1
        }
    }
    return result * signs
}
```
### Time Complexity:
O(n)
### Space Complexity:
O(1)

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var negativeCount = 0
    for element in arr {
        if element > 0 {
            result *= element
        } else if element < 0 {
            negativeCount += 1
        }
    }
    
    if negativeCount % 2 == 0 {
        return result
    } else {
        return -result
    }
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var negativeCount = 0
    for element in arr {
        if element > 0 {
            result *= element
        } else if element < 0 {
            negativeCount += 1
        }
    }
    
    if negativeCount % 2 == 0 {
        return result
    } else {
        return -result
    }
}
```
### Time Complexity:
O(n)
### Space Complexity:
O(1)

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    var result = 1
    var sign = 1
    for element in arr {
        result *= element
        if element > 0 {
            sign *= 1
        } else if element < 0 {
            sign *= -1
        }
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    var result = 1
    var sign = 1
    for element in arr {
        result *= element
        if element > 0 {
            sign *= 1
        } else if element < 0 {
            sign *= -1
        }
    }
    return result * sign
}
```
### Time Complexity:
O(n)
### Space Complexity:
O(1)

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var sign = 1
    
    for element in arr {
        if element > 0 {
            result *= element
            sign *= 1
        } else if element < 0 {
            result *= -element
            sign *= -1
        }
    }
    
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var sign = 1
    
    for element in arr {
        if element > 0 {
            result *= element
            sign *= 1
        } else if element < 0 {
            result *= -element
            sign *= -1
        }
    }
    
    return result * sign
}
```
### Time Complexity:
O(n)
### Space Complexity:
O(1)

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    var result = 1
    var sign = 1
    for element in arr {
        result *= element
        if element > 0 {
            sign *= 1
        } else if element < 0 {
            sign *= -1
        }
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    var result = 1
    var sign = 1
    for element in arr {
        result *= element
        if element > 0 {
            sign *= 1
        } else if element < 0 {
            sign *= -1
        }
    }
    return result * sign
}
```
### Time Complexity:
O(n)
### Space Complexity:
O(1)

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    var result = 1
    var sign = 1
    for element in arr {
        if element > 0 {
            result *= element
            sign *= 1
        } else if element < 0 {
            result *= -element
            sign *= -1
        }
    }
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    var result = 1
    var sign = 1
    for element in arr {
        if element > 0 {
            result *= element
            sign *= 1
        } else if element < 0 {
            result *= -element
            sign *= -1
        }
    }
    return result * sign
}
```
### Time Complexity:
O(n)
### Space Complexity:
O(1)

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var negativeCount = 0
    for element in arr {
        if element > 0 {
            result *= element
        } else if element < 0 {
            negativeCount += 1
        }
    }
    
    if negativeCount % 2 == 0 {
        result *= 1
    } else {
        result *= -1
    }
    
    return result
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var negativeCount = 0
    for element in arr {
        if element > 0 {
            result *= element
        } else if element < 0 {
            negativeCount += 1
        }
    }
    
    if negativeCount % 2 == 0 {
        result *= 1
    } else {
        result *= -1
    }
    
    return result
}
```
### Time Complexity:
O(n)
### Space Complexity:
O(1)

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var signs = 0
    
    for element in arr {
        result *= element
        if element > 0 {
            signs += 1
        } else if element < 0 {
            signs -= 1
        }
    }
    
    return result * signs
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var signs = 0
    
    for element in arr {
        result *= element
        if element > 0 {
            signs += 1
        } else if element < 0 {
            signs -= 1
        }
    }
    
    return result * signs
}
```
### Time Complexity:
O(n)
### Space Complexity:
O(1)

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var negativeCount = 0
    for num in arr {
        if num > 0 {
            result *= num
        } else if num < 0 {
            negativeCount += 1
        }
    }
    
    if negativeCount % 2 == 0 {
        result *= 1
    } else {
        result *= -1
    }
    
    return result
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var negativeCount = 0
    for num in arr {
        if num > 0 {
            result *= num
        } else if num < 0 {
            negativeCount += 1
        }
    }
    
    if negativeCount % 2 == 0 {
        result *= 1
    } else {
        result *= -1
    }
    
    return result
}
```
### Time Complexity:
O(n)
### Space Complexity:
O(1)

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var sign = 1
    
    for element in arr {
        result *= element
        if element > 0 {
            sign *= 1
        } else if element < 0 {
            sign *= -1
        }
    }
    
    return result * sign
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    // Write your code here
    if arr.isEmpty {
        return nil
    }
    
    var result = 1
    var sign = 1
    
    for element in arr {
        result *= element
        if element > 0 {
            sign *= 1
        } else if element < 0 {
            sign *= -1
        }
    }
    
    return result * sign
}
```
### Time Complexity:
O(n)
### Space Complexity:
O(1)

 // XCTAssertTrue failed

Problem #145 Experiment #203

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

func sum(a: Int, b: Int) -> Int {
    if a == b {
        return a
    }
    if a < b {
        return (a + 1) * (b - a) / 2
    }
    return (b + 1) * (a - b) / 2
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

// -----------------------------------------------------------------------------

// https://www.codewars.com/kata/55f2b114941f82c5db0000a3/train/swift
// Given two integers a and b, which can be positive or negative,
// find the sum of all the integers between and including them
// and return it. If the two numbers are equal return a or b.
// Note: a and b are not ordered!
// Examples (a, b) --> output (explanation)
// (1, 2) --> 3 (1 + 2)
// (1, 1) --> 1 (1 + 1)
// (1, 0) --> 1 (1 + 0)
// (0, 0) --> 0 (0 + 0)
// (0, 1) --> 1 (0 + 1)

func sum(a: Int, b: Int) -> Int {
    if a == b {
        return a
    }
    if a < b {
        return (a + 1) * (b - a) / 2
    }
    return (b + 1) * (a - b) / 2
}

// -----------------------------------------------------------------------------

// https://www.codewars.com/kata/55f2b114941f81a77b0000d3/train/swift
// Given two integers a and b, which can be positive or negative,
// find the sum of all the integers between and including them
// and return it. If the two numbers are equal return a or b.
// Note: a and b are not ordered!
// Examples (a, b) --> output (explanation)
// (1, 2) --> 3 (1 + 2)
// (1, 1) --> 1 (1 + 1)
// (1, 0) --> 1 (1 + 0)
// (0, 0) --> 0 (0 + 0)
// (0, 1) --> 1 (0 + 1)

func sum(a: Int, b: Int) -> Int {
    if a == b {
        return a
    }
    if a < b {
        return (a + 1) * (b - a) / 2
    }
    return (b + 1) * (a - b) / 2
}

// -----------------------------------------------------------------------------

// https://www.codewars.com/kata/55f2b863d63c2e6abcd00003c/train/swift
// Given two integers a and b, which can be positive or negative,
// find the sum of all the integers between and including them
// and return it. If the two numbers are equal return a or b.
// Note: a and b are not ordered!
// Examples (a, b) --> output (explanation)
// (1, 2) --> 3 (1 + 2)
// (1, 1) --> 1 (1 + 1)
// (1, 0) --> 1 (1 + 0)
// (0, 0) --> 0 (0 + 0)
// (0, 1) --> 1 (0 + 1)

func sum(a: Int, b: Int) -> Int {
    if a == b {
        return a
    }
    if a < b {
        return (a + 1) * (b - a) / 2
    }
    return (b + 1) * (a -

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

func longestSubstring(s: String) -> Int {
    var max = 0
    var start = 0
    var map = [Int: Int]()
    for i in range(0, s.count) {
        if map[s[i]] != nil {
            start = max(start, map[s[i]] + 1)
        }
        max = max(max, i - start + 1)
        map[s[i]] = i
    }
    return max
}

func longestPalindrome(s: String) -> String {
    var max = ""
    for i in range(0, s.count) {
        for j in range(i, s.count) {
            var sub = s[i..<j]
            if sub == sub.reversed() {
                if sub.count > max.count {
                    max = sub
                }
            }
        }
    }
    return max
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

// 2.
// Given a string, find the length of the longest substring without repeating characters.
// Example:
// longestSubstring("abcabcbb") == 3
// longestSubstring("bbbbb") == 1
// longestSubstring("pwwkew") == 3
func longestSubstring(s: String) -> Int {
    var max = 0
    var start = 0
    var map = [Int: Int]()
    for i in range(0, s.count) {
        if map[s[i]] != nil {
            start = max(start, map[s[i]] + 1)
        }
        max = max(max, i - start + 1)
        map[s[i]] = i
    }
    return max
}

// 3.
// Given a string s, find the longest palindromic substring in s.
// You may assume that the maximum length of s is 1000.
// Example:
// longestPalindrome("babad") == "bab"
// longestPalindrome("cbbd") == "bb"
func longestPalindrome(s: String) -> String {
    var max = ""
    for i in range(0, s.count) {
        for j in range(i, s.count) {
            var sub = s[i..<j]
            if sub == sub.reversed() {
                if sub.count > max.count {
                    max = sub
                }
            }
        }
    }
    return max
}

// 4.
// Given a string s, find the longest palindromic substring in s.
// You may assume that the maximum length of s is 1000.
// Example:
// longestPalindrome("babad") == "bab"
// longestPalindrome("cbbd") == "bb"
func longestPalindrome(s: String) -> String {
    var max = ""
    for i in range(0, s.count) {
        for j in range(i, s.count) {
            var sub = s[i..<j]
            if sub == sub.reversed() {
                if sub.count > max.count {
                    max = sub
                }
            }
        }
    }
    return max
}

// 5.
// Given a string s, find the longest palindromic substring in s.
// You may assume that the maximum length of s is 1000.
// Example:
// longestPalindrome("babad") == "bab"
// longestPalindrome("cbbd") == "bb"
func longestPalindrome(s: String) -> String {
    var max = ""
    for i in range(0, s.count) {
        for j in range(i, s.count) {
            var sub = s[i..<j]
            if sub == sub.reversed() {
                if sub.count > max.count {
                    max = sub
                }
            }
        }
    }
    return max
}

// 6.
// Given a string s, find the longest palindromic substring in s.
// You may assume that the maximum length of s is 1000.
// Example:
// longestPalindrome("babad") == "bab"
// longestPalindrome("cbbd") == "bb"
func longestPalindrome(s: String) -> String {
    var max = ""
    for i in range(0, s.count) {
        for j in range(i, s.count) {
            var sub = s[i..<j]
            if sub == sub.reversed() {
                if sub.count > max.count {
                    max = sub
                }
            }

for i in range(0, s.count) { // cannot find 'range' in scope

for i in range(0, s.count) { // cannot find 'range' in scope

for j in range(i, s.count) { // cannot find 'range' in scope

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    let sum = 0
    let product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += 1
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    let sum = 0
    let product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += 1
    }
    return sum * product
}

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// ---------

product *= -1 // left side of mutating operator isn't mutable: 'product' is a 'let' constant

sum += 1 // left side of mutating operator isn't mutable: 'sum' is a 'let' constant

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 1
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += 1
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 1
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += 1
    }
    return sum * product
}

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// ------------------------------------------------------------------------

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            sum += 1
        } else if i > 0 {
            product *= i
        } else {
            product *= -i
        }
    }
    return sum == 0 ? 0 : product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            sum += 1
        } else if i > 0 {
            product *= i
        } else {
            product *= -i
        }
    }
    return sum == 0 ? 0 : product
}

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// ---------------------------------------------------------

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 1
    var product = 1
    for i in arr {
        if i == 0 {
            return 0
        }
        if i < 0 {
            product *= -1
        }
        sum += i
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 1
    var product = 1
    for i in arr {
        if i == 0 {
            return 0
        }
        if i < 0 {
            product *= -1
        }
        sum += i
    }
    return sum * product
}

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

// ------

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 1
    var product = 1
    for i in arr {
        if i == 0 {
            return 0
        }
        if i > 0 {
            sum += 1
        }
        if i < 0 {
            product *= -1
        }
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 1
    var product = 1
    for i in arr {
        if i == 0 {
            return 0
        }
        if i > 0 {
            sum += 1
        }
        if i < 0 {
            product *= -1
        }
    }
    return sum * product
}

// -----------------------------------------------------------------------------
// 1.1.2
// -----------------------------------------------------------------------------
// Given an array of integers, find the one that appears an odd number of times.
// There will always be only one integer that appears an odd number of times.
// Examples
// [7] should return 7, because it occurs 1 time (which is odd).
// [0] should return 0, because it occurs 1 time (which is odd).
// [1,1,2] should return 2, because it occurs 1 time (which is odd).
// [0,1,0,1,0] should return 0, because it occurs 3 times (which is odd).
// [1,2,2,3,3,3] should return 3.
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
//

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 1
    var product = 1
    for i in arr {
        if i == 0 {
            product = 0
        } else if i > 0 {
            sum *= i
        } else {
            sum *= -i
        }
    }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 1
    var product = 1
    for i in arr {
        if i == 0 {
            product = 0
        } else if i > 0 {
            sum *= i
        } else {
            sum *= -i
        }
    }
    return sum * product
}

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            return 0
        }
        if i < 0 {
            sum += 1
        }
        product *= i
    }
    return sum % 2 == 0 ? product : -product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            return 0
        }
        if i < 0 {
            sum += 1
        }
        product *= i
    }
    return sum % 2 == 0 ? product : -product
}

// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
// ---------------------------------------------------------------------

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

struct MagnitudeProduct {
    var sum: Int
    var product: Int
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

// -----------------------------------------------------------------------------

struct MagnitudeProduct {
    var sum: Int
    var product: Int
}

// -----------------------------------------------------------------------------

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

// -----------------------------------------------------------------------------

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

// -----------------------------------------------------------------------------

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

// -----------------------------------------------------------------------------

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

// -----------------------------------------------------------------------------

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

// -----------------------------------------------------------------------------

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var product = 1
    for i in arr {
        if i == 0 {
            continue
        }
        if i < 0 {
            product *= -1
        }
        sum += abs(i)
    }
    return sum * product
}

// -----------------------------------------------------------------------------

func prodSigns(arr: [Int]) -> Int? {
    if arr.count == 0 {
        return nil
    }
    var sum = 0
    var

 // XCTAssertTrue failed

Problem #145 Experiment #204

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += 1
        }
    }
    
    return sum * product
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += 1
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
            sum += 1
        } else if num < 0 {
            product *= num
            sum -= 1
        }
    }
    
    return sum * product
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
            sum += 1
        } else if num < 0 {
            product *= num
            sum -= 1
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        if num > 0 {
            product *= num
        } else if num < 0 {
            sum += abs(num)
        }
    }
    
    return sum * product
}
```

 // XCTAssertTrue failed

Problem #145 Experiment #206

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}

user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var productOfSigns: Int = 1
    var sumOfMagnitudes: Int = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        productOfSigns *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return productOfSigns * sumOfMagnitudes
}
```

Problem #145 Experiment #207

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, { $0 * $1 })
    let sign = product > 0 ? 1 : product < 0 ? -1 : 0
    return arr.map { $0 * sign }.reduce(0, +)
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, { $0 * $1 })
    let sign = product > 0 ? 1 : product < 0 ? -1 : 0
    return arr.map { $0 * sign }.reduce(0, +)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= signum(num)
        sum += abs(num)
    }
    return product * sum
}

func signum(_ num: Int) -> Int {
    if num > 0 { return 1 }
    if num < 0 { return -1 }
    return 0
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= signum(num)
        sum += abs(num)
    }
    return product * sum
}

func signum(_ num: Int) -> Int {
    if num > 0 { return 1 }
    if num < 0 { return -1 }
    return 0
}
```

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    let signProduct = arr.reduce(1, { $0 * ($1 > 0 ? 1 : ($1 < 0 ? -1 : 0)) })
    let magnitudeSum = arr.reduce(0, { $0 + abs($1) })
    return magnitudeSum * signProduct
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty { return nil }
    let signProduct = arr.reduce(1, { $0 * ($1 > 0 ? 1 : ($1 < 0 ? -1 : 0)) })
    let magnitudeSum = arr.reduce(0, { $0 + abs($1) })
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        }
        product *= num < 0 ? -1 : 1
        sum += abs(num)
    }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        if num == 0 {
            product = 0
            break
        }
        product *= num < 0 ? -1 : 1
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num > 0 ? 1 : num < 0 ? -1 : 0
        sum += abs(num)
    }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= num > 0 ? 1 : num < 0 ? -1 : 0
        sum += abs(num)
    }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= signum(num)
        sum += abs(num)
    }
    return product * sum
}

func signum(_ num: Int) -> Int {
    if num > 0 { return 1 }
    if num < 0 { return -1 }
    return 0
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= signum(num)
        sum += abs(num)
    }
    return product * sum
}

func signum(_ num: Int) -> Int {
    if num > 0 { return 1 }
    if num < 0 { return -1 }
    return 0
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, { $0 * $1 })
    let sum = arr.map { $0 * abs($0) }.reduce(0, +)
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, { $0 * $1 })
    let sum = arr.map { $0 * abs($0) }.reduce(0, +)
    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, { $0 * $1 })
    let sum = arr.reduce(0, { $0 + abs($1) })
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1, { $0 * $1 })
    let sum = arr.reduce(0, { $0 + abs($1) })
    return product * sum
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= signum(num)
        sum += abs(num)
    }
    return product * sum
}

func signum(_ num: Int) -> Int {
    if num > 0 { return 1 }
    if num < 0 { return -1 }
    return 0
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= signum(num)
        sum += abs(num)
    }
    return product * sum
}

func signum(_ num: Int) -> Int {
    if num > 0 { return 1 }
    if num < 0 { return -1 }
    return 0
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= signum(num)
        sum += abs(num)
    }
    return sum * product
}

func signum(_ num: Int) -> Int {
    if num > 0 { return 1 }
    if num < 0 { return -1 }
    return 0
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    var product = 1
    var sum = 0
    for num in arr {
        product *= signum(num)
        sum += abs(num)
    }
    return sum * product
}

func signum(_ num: Int) -> Int {
    if num > 0 { return 1 }
    if num < 0 { return -1 }
    return 0
}
```

Problem #145 Experiment #208

func prodSigns(arr: [Int]) -> Int? {
    // Your code here
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // Your code here
}
```

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let sum = arr.reduce(0, +)
    let product = arr.reduce(1) { $0 * ($1 > 0 ? 1 : ($1 < 0 ? -1 : 0)) }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let sum = arr.reduce(0, +)
    let product = arr.reduce(1) { $0 * ($1 > 0 ? 1 : ($1 < 0 ? -1 : 0)) }
    return sum * product
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.map { abs($0) }.reduce(0, +)
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.map { abs($0) }.reduce(0, +)
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}
```

func prodSigns(arr: [Int]) -> Int? {
    // Your code here
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    // Your code here
}
```

} // missing return in global function expected to return 'Int?'

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let sum = arr.reduce(0) { $0 + abs($1) }
    let product = arr.reduce(1) { $0 * ($1.signum() ?? 1) }
    return sum * product
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let sum = arr.reduce(0) { $0 + abs($1) }
    let product = arr.reduce(1) { $0 * ($1.signum() ?? 1) }
    return sum * product
}
```

let product = arr.reduce(1) { $0 * ($1.signum() ?? 1) } // left side of nil coalescing operator '??' has non-optional type 'Int', so the right side is never used

func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}

```swift
// You are given an array arr of integers and you need to return
// sum of magnitudes of integers multiplied by product of all signs
// of each number in the array, represented by 1, -1 or 0.
// Note: return nil for empty arr.
// Example:
// prodSigns(arr: [1, 2, 2, -4]) == 9
// prodSigns(arr: [0, 1]) == 0
// prodSigns(arr: [] as [Int]) == nil
func prodSigns(arr: [Int]) -> Int? {
    guard !arr.isEmpty else { return nil }
    let product = arr.reduce(1) { $0 * $1.signum() }
    let sum = arr.reduce(0) { $0 + abs($1) }
    return product * sum
}
```

Problem #145 Experiment #209

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    return abs(signProduct) * sumOfMagnitudes(arr)
}

func sumOfMagnitudes(arr: [Int]) -> Int {
    var sum = 0
    
    for num in arr {
        sum += abs(num)
    }
    
    return sum
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    return abs(signProduct) * sumOfMagnitudes(arr)
}

func sumOfMagnitudes(arr: [Int]) -> Int {
    var sum = 0
    
    for num in arr {
        sum += abs(num)
    }
    
    return sum
}
```

return abs(signProduct) * sumOfMagnitudes(arr) // missing argument label 'arr:' in call

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    return abs(signProduct) * sumOfMagnitudes(arr)
}

func sumOfMagnitudes(arr: [Int]) -> Int {
    var sum = 0
    
    for num in arr {
        sum += abs(num)
    }
    
    return sum
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    return abs(signProduct) * sumOfMagnitudes(arr)
}

func sumOfMagnitudes(arr: [Int]) -> Int {
    var sum = 0
    
    for num in arr {
        sum += abs(num)
    }
    
    return sum
}
```

return abs(signProduct) * sumOfMagnitudes(arr) // missing argument label 'arr:' in call

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        signProduct *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return signProduct * sumOfMagnitudes
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        signProduct *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return signProduct * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        signProduct *= (num > 0 ? 1 : -1)
    }
    
    return abs(signProduct)
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        signProduct *= (num > 0 ? 1 : -1)
    }
    
    return abs(signProduct)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        signProduct *= (num > 0 ? 1 : -1)
    }
    
    return abs(signProduct)
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        signProduct *= (num > 0 ? 1 : -1)
    }
    
    return abs(signProduct)
}
```

 // XCTAssertTrue failed

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        signProduct *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return signProduct * sumOfMagnitudes
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    var sumOfMagnitudes = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        signProduct *= (num > 0 ? 1 : -1)
        sumOfMagnitudes += abs(num)
    }
    
    return signProduct * sumOfMagnitudes
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    let magnitudeSum = arr.map { abs($0) }.reduce(0, +)
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    let magnitudeSum = arr.map { abs($0) }.reduce(0, +)
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    let sumOfMagnitudes = arr.map { abs($0) }.reduce(0, +)
    
    return sumOfMagnitudes * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    let sumOfMagnitudes = arr.map { abs($0) }.reduce(0, +)
    
    return sumOfMagnitudes * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    let magnitudeSum = arr.map { abs($0) }.reduce(0, +)
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    let magnitudeSum = arr.map { abs($0) }.reduce(0, +)
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    let magnitudeSum = arr.map { abs($0) }.reduce(0, +)
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var signProduct = 1
    
    for num in arr {
        if num == 0 {
            return 0
        } else if num < 0 {
            signProduct *= -1
        }
    }
    
    let magnitudeSum = arr.map { abs($0) }.reduce(0, +)
    
    return magnitudeSum * signProduct
}
```

Problem #145 Experiment #210

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { return nil }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { 
        return nil 
    } 

    let magnitudeSum = arr.map(abs).reduce(0, +) 
    let signProduct = arr.reduce(1) { $0 * ($1 > 0 ? 1 : ($1 < 0 ? -1 : 0)) } 

    return magnitudeSum * signProduct 
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { 
        return nil 
    } 

    let magnitudeSum = arr.map(abs).reduce(0, +) 
    let signProduct = arr.reduce(1) { $0 * ($1 > 0 ? 1 : ($1 < 0 ? -1 : 0)) } 

    return magnitudeSum * signProduct 
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { 
        return nil 
    } 

    var magnitudeSum = 0 
    var signProduct = 1 

    for num in arr { 
        magnitudeSum += abs(num) 
        if num < 0 { 
            signProduct *= -1 
        } else if num == 0 { 
            signProduct = 0 
            break 
        } 
    } 

    return magnitudeSum * signProduct 
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else { 
        return nil 
    } 

    var magnitudeSum = 0 
    var signProduct = 1 

    for num in arr { 
        magnitudeSum += abs(num) 
        if num < 0 { 
            signProduct *= -1 
        } else if num == 0 { 
            signProduct = 0 
            break 
        } 
    } 

    return magnitudeSum * signProduct 
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    let magnitudeSum = arr.map(abs).reduce(0, +)
    let signProduct = arr.reduce(1) { $0 * ($1 > 0 ? 1 : ($1 < 0 ? -1 : 0)) }
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    let magnitudeSum = arr.map(abs).reduce(0, +)
    let signProduct = arr.reduce(1) { $0 * ($1 > 0 ? 1 : ($1 < 0 ? -1 : 0)) }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    var magnitudeSum = 0
    var signProduct = 1
    
    for num in arr {
        magnitudeSum += abs(num)
        
        if num < 0 {
            signProduct *= -1
        } else if num == 0 {
            signProduct = 0
            break
        }
    }
    
    return magnitudeSum * signProduct
}
```

func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    let magnitudeSum = arr.map(abs).reduce(0, +)
    let signProduct = arr.reduce(1) { $0 * ($1 > 0 ? 1 : ($1 < 0 ? -1 : 0)) }
    
    return magnitudeSum * signProduct
}

system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.
user
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
assistant
```swift
func prodSigns(arr: [Int]) -> Int? { 
    guard !arr.isEmpty else {
        return nil
    }
    
    let magnitudeSum = arr.map(abs).reduce(0, +)
    let signProduct = arr.reduce(1) { $0 * ($1 > 0 ? 1 : ($1 < 0 ? -1 : 0)) }
    
    return magnitudeSum * signProduct
}
```

Problem #145 Experiment #211

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num < 0? -1 : (num > 0? 1 : 0)
    }
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var sum = 0
    var product = 1
    for num in arr {
        sum += abs(num)
        product *= num < 0? -1 : (num > 0? 1 : 0)
    }
    return sum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

product *= num < 0? -1 : (num > 0? 1 : 0) // expected expression

product *= num < 0? -1 : (num > 0? 1 : 0) // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : (num > 0? 1 : 0) // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : (num > 0? 1 : 0) // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : (num > 0? 1 : 0) // integer literal is unused

product *= num < 0? -1 : (num > 0? 1 : 0) // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : (num > 0? 1 : 0) // cannot convert value of type 'Bool' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var magnitudeSum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        }
        
        product *= num < 0? -1 : 1
        magnitudeSum += abs(num)
    }
    
    return product * magnitudeSum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var magnitudeSum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        }
        
        product *= num < 0? -1 : 1
        magnitudeSum += abs(num)
    }
    
    return product * magnitudeSum
}
```

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty {
    return nil
  }
  var sum = 0
  var product = 1
  for num in arr {
    sum += abs(num)
    if num!= 0 {
      product *= num > 0? 1 : -1
    }
  }
  return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
  if arr.isEmpty {
    return nil
  }
  var sum = 0
  var product = 1
  for num in arr {
    sum += abs(num)
    if num!= 0 {
      product *= num > 0? 1 : -1
    }
  }
  return sum * product
}
```

if num!= 0 { // cannot force unwrap value of non-optional type 'Int'

if num!= 0 { // use of '=' in a boolean context, did you mean '=='?

if num!= 0 { // '=' must have consistent whitespace on both sides

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : -1 // integer literal is unused

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : -1 // expected expression

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var magnitudeSum = 0
    
    for num in arr {
        if num!= 0 {
            product *= num > 0? 1 : -1
        }
        
        magnitudeSum += abs(num)
    }
    
    return magnitudeSum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var magnitudeSum = 0
    
    for num in arr {
        if num!= 0 {
            product *= num > 0? 1 : -1
        }
        
        magnitudeSum += abs(num)
    }
    
    return magnitudeSum * product
}
```

if num!= 0 { // cannot force unwrap value of non-optional type 'Int'

if num!= 0 { // use of '=' in a boolean context, did you mean '=='?

if num!= 0 { // '=' must have consistent whitespace on both sides

product *= num > 0? 1 : -1 // expected expression

product *= num > 0? 1 : -1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num > 0? 1 : -1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num > 0? 1 : -1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num > 0? 1 : -1 // integer literal is unused

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

product *= num > 0? 1 : -1 // consecutive statements on a line must be separated by ';'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var magnitudeSum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        }
        
        product *= num < 0? -1 : 1
        magnitudeSum += abs(num)
    }
    
    return product * magnitudeSum
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var magnitudeSum = 0
    
    for num in arr {
        if num == 0 {
            product = 0
            break
        }
        
        product *= num < 0? -1 : 1
        magnitudeSum += abs(num)
    }
    
    return product * magnitudeSum
}
```

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        
        if num!= 0 {
            product *= num < 0? -1 : 1
        }
    }
    
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        
        if num!= 0 {
            product *= num < 0? -1 : 1
        }
    }
    
    return sum * product
}
```

if num!= 0 { // cannot force unwrap value of non-optional type 'Int'

if num!= 0 { // '=' must have consistent whitespace on both sides

if num!= 0 { // use of '=' in a boolean context, did you mean '=='?

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        
        if num!= 0 {
            product *= num < 0? -1 : 1
        }
    }
    
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        
        if num!= 0 {
            product *= num < 0? -1 : 1
        }
    }
    
    return sum * product
}
```

if num!= 0 { // cannot force unwrap value of non-optional type 'Int'

if num!= 0 { // '=' must have consistent whitespace on both sides

if num!= 0 { // use of '=' in a boolean context, did you mean '=='?

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var magnitudeSum = 0
    for num in arr {
        if num!= 0 {
            product *= num < 0? -1 : 1
        }
        magnitudeSum += abs(num)
    }
    return magnitudeSum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    guard!arr.isEmpty else { return nil }
    var product = 1
    var magnitudeSum = 0
    for num in arr {
        if num!= 0 {
            product *= num < 0? -1 : 1
        }
        magnitudeSum += abs(num)
    }
    return magnitudeSum * product
}
```

guard!arr.isEmpty else { return nil } // expected expression, var, let or case in 'guard' condition

if num!= 0 { // use of '=' in a boolean context, did you mean '=='?

if num!= 0 { // cannot force unwrap value of non-optional type 'Int'

if num!= 0 { // '=' must have consistent whitespace on both sides

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // integer literal is unused

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // expected expression

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var magnitudeSum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        product *= num < 0? -1 : 1
        magnitudeSum += abs(num)
    }
    
    return magnitudeSum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var product = 1
    var magnitudeSum = 0
    
    for num in arr {
        if num == 0 {
            return 0
        }
        
        product *= num < 0? -1 : 1
        magnitudeSum += abs(num)
    }
    
    return magnitudeSum * product
}
```

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        
        if num!= 0 {
            product *= num < 0? -1 : 1
        }
    }
    
    return sum * product
}

### Instruction:
Write code in Swift programming language. Don't include usage examples or tests.
You are given an array arr of integers and you need to return
sum of magnitudes of integers multiplied by product of all signs
of each number in the array, represented by 1, -1 or 0.
Note: return nil for empty arr.
Example:
prodSigns(arr: [1, 2, 2, -4]) == 9
prodSigns(arr: [0, 1]) == 0
prodSigns(arr: [] as [Int]) == nil
### Response:
```swift
func prodSigns(arr: [Int]) -> Int? {
    if arr.isEmpty {
        return nil
    }
    
    var sum = 0
    var product = 1
    
    for num in arr {
        sum += abs(num)
        
        if num!= 0 {
            product *= num < 0? -1 : 1
        }
    }
    
    return sum * product
}
```

if num!= 0 { // cannot force unwrap value of non-optional type 'Int'

if num!= 0 { // '=' must have consistent whitespace on both sides

if num!= 0 { // use of '=' in a boolean context, did you mean '=='?

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // expected expression

product *= num < 0? -1 : 1 // consecutive statements on a line must be separated by ';'

product *= num < 0? -1 : 1 // cannot convert value of type 'Bool' to expected argument type 'Int'

product *= num < 0? -1 : 1 // cannot use optional chaining on non-optional value of type 'Int'

product *= num < 0? -1 : 1 // value of optional type 'Int?' must be unwrapped to a value of type 'Int'

product *= num < 0? -1 : 1 // integer literal is unused

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