swift - 在 Swift 中解决 HackerRank 的对角差分问题 - 为什么它不起作用？

Question

我正在挑战黑客排名，想知道为什么我会出现运行时错误，甚至是错误的答案。问题是:

Given a square matrix, calculate the absolute difference between the sums of its diagonals.

Example:
3
11 2 4
4 5 6
10 8 -12


output: 15

(The first line contains a single integer, the number of rows and columns in the matrix arr).

这是我的代码:

func diagonalDifference(arr: [[Int]]) -> Int {
    let n = arr[0][0]
    var diagonal1 = 0
    var diagonal2 = 0
    for index in 1...n {
        diagonal1 += arr[index][index - 1]
        diagonal2 += arr[index][n - index]
    }
    return abs(diagonal1 - diagonal2)
}

我似乎无法找到它不起作用的原因。

Answer 1

我对输入的输入方式有同样的问题，但这个解决方案有效。

func diagonalDifference(arr: [[Int]]) -> Int {
 var n =  arr.count
 var primaryDiagonalSum = 0
 var secondaryDiagonalSum = 0

     for index in 0..<n {
primaryDiagonalSum   +=  arr[index][index]
secondaryDiagonalSum +=  arr[index][n-index-1]
                         }  
 
    let difference = abs(primaryDiagonalSum - secondaryDiagonalSum)
    return difference
                                              }