Diagonal Difference Hacker Rank Solution Best & Easiest

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

or example, the square matrix arr 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 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

Diagonal Difference Hacker Rank Solution:

Problem solution in C++ programming

int diagonalDifference(vector<vector<int>> arr) {

    size_t size = arr[0].size();
    int sum{};
    int i=0;
    
    for(const auto& vec : arr)    
        sum+= (vec[size-1-i] - vec[i++]);
        
    return abs(sum);
}

Problem solution in JavaScript programming

function diagonalDifference(arr) {
    // Write your code here
    let first_diagonal = 0, second_diagonal = 0
    let len = arr.length - 1 
    for(let i=0; i<arr.length; i++){
        first_diagonal += arr[i][i];
        second_diagonal += arr[i][len-i];
    }
    let res = first_diagonal - second_diagonal
    return Math.abs(res)
}

Problem solution in Python programming

def diagonalDifference(arr):      Write your code here
    first_diagonal = second_diagonal = 0
    # Time: O(n)
    # Space: O(1)
    for i in range(len(arr)):
        first_diagonal += arr[i][i]
        second_diagonal += arr[i][len(arr) - 1 - i]
    return abs(first_diagonal - second_diagonal)