Diagonal Difference Solution in Kotlin -HackerRank

Problem

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

Input Format

The first line contains a single integer, N. The next N lines denote the matrix’s rows, with each line containing N space-separated integers describing the columns.

Constraints

• -100 < Elements in the matrix < 100

Output Format

Print the absolute difference between the two sums of the matrix’s diagonals as a single integer.

Sample Input

3 
11 2 4 
4 5 6 
10 8 -12

Sample Output

15

ANSWER

fun diagonalDifference(arr: Array<Array<Int>>): Int {
    // Write your code here
    var rightDiagonal = 0
    var leftDiagonal = 0
    for (x in 0 until arr.size) {
        rightDiagonal += arr[x][arr.size-1-x]
        leftDiagonal += arr[x][x]
    }
return  Math.abs(leftDiagonal - rightDiagonal) // integer value still positive
}

Explanation

11   
  5     
   -12

Sum across the primary diagonal: 11 + 5–12 = 4

The secondary diagonal is:

   4   
  5 
10

Sum across the secondary diagonal: 4 + 5 + 10 = 19

Difference: |4–19| = 15