Here is problem solution in Python, Java, C++, C and Javascript - https://programmingoneonone.com/hackerrank-diagonal-difference-problem-solution.html

TypeScript

function diagonalDifference(arr: number[][]): number {
    let diag1 = 0;
    let diag2 = 0;
    for (let i = 0; i < arr.length; i++) {
        diag1 += arr[i][i];
        diag2 += arr[i][arr.length - 1 - i];
    }
    return Math.abs(diag1 - diag2);
}
const input = require("fs").readFileSync(0, 'utf-8').split('\n');
const n = parseInt(input[0]);
const matrix: number[][] = [];

for (let i = 1; i <= n; i++) {
    matrix.push(input[i].split(' ').map(Number));
}

console.log(diagonalDifference(matrix));

in C++ int diagonalDifference(vector> arr) { int sum=0; for(int i=0;i sum=sum-arr[i][arr.size()-1-i]; } if (sum<0) { sum=sum*(-1); } return sum; }

public static int diagonalDifference(List<List<Integer>> arr) {
    int leftSum = 0;
    int rightSum = 0;
    int matrixSize = arr.size();
    for (int i = 0; i < matrixSize; i++) {
        leftSum += arr.get(i).get(i);
        rightSum += arr.get(i).get(matrixSize -1 - i);
    }
    return bitwiseAbs(leftSum - rightSum);
}

private static int bitwiseAbs(int n) {
    return (n ^ (n >> 31)) - (n >> 31);
}

Here is problem solution in Python java c++ c and javascript - https://programmingoneonone.com/hackerrank-diagonal-difference-problem-solution.html