[Assesment] - hackerrank-diagonal-difference

README.md

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

For example, the square matrix

is shown below:

1 2 3
4 5 6
9 8 9  

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

Function description

Complete the 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, , and consists of 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

index.js

/**
 * arr: Array<Array<integer>>
 */
function diagonalDifference(arr) {
    const childArrayLength = arr[0].length;
    let firstDiagonalSum = 0;
    let secondDiagonalSum = 0;
    
    for (let i = 0, j = (childArrayLength - 1); i < childArrayLength, j > -1; i++, j--){ 
        firstDiagonalSum += arr[i][i]
        secondDiagonalSum += arr[i][j]
    } 
    
    let diff = secondDiagonalSum - firstDiagonalSum;
    
    if (diff < 0) {
        return -(diff)
    }
    
    return diff;
}