05-Diagonal_Difference.md

Problem

Given a square matrix, calculate the absolute difference between the sums of its diagonals. For example, the square matrix arr is shown below:

1 2 3
4 5 6
9 8 9

The left-to-right diagonal is 1 + 5 + 9 = 15. The right-to-left diagonal is 3 + 5 + 9 = 17. Their absolute difference is |15 - 17| = 2.

Function description

Complete the diagonalDifference function in the editor below.

diagonalDifference takes the following parameter:

• int arr[n][m]: an array of integers

Return

• int: the absolute diagonal difference

Input Format

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

Each of the next n lines describes a row, arr[i], and consists of n space-separated integers arr[i][j].

Constraints

• -100 <= arr[i][j] <= 100

Output Format

Return the absolute difference between the sums of the matrix's two diagonals as a single integer.

Sample Input

3
11 2 4
4 5 6
10 8 -12

Sample Output

15

Explanation

The primary diagonal is:

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

Note: |x| is the absolute value of x.