Swift: easy to read O(n)

func diagonalDifference(arr: [[Int]]) -> Int { // Write your code here let length = arr.count var leftDiagnolSum = 0 var rightDiagnolSum = 0

for i in (0..<length) {
    leftDiagnolSum += arr[i][i]
    rightDiagnolSum += arr[(length - 1) - i][i]
}

let difference = leftDiagnolSum - rightDiagnolSum
return difference >= 0 ? difference : difference * -1

}