Problems

Question:

Principal Diagonal — The principal diagonal in a matrix identifies those elements of the matrix running from North-West to South-East.

Secondary Diagonal — the secondary diagonal of amatrix identifies those elements of the matrix running from North-East to South-West.

For example:

matrix: [1, 2, 3] [4, 5, 6] [7, 8, 9]

principal diagonal: [1, 5, 9]

econdary diagonal: [3, 5, 7]

Task

Your task is to find which diagonal is “larger”: which diagonal has a bigger sum of their elements.

• If the principal diagonal is larger, return "Principal Diagonal win!"
• If the secondary diagonal is larger, return "Secondary Diagonal win!"
• If they are equal, return "Draw!"

Note: You will always receive matrices of the same dimension.

Solution:

function diagonal(matrix){
    var sumNw=0, sumNe = 0;
    for (var i=0; i<matrix.length; i++) {
        sumNw += matrix[i][i];
        sumNe += matrix[i][matrix.length-1-i];
    }
    if (sumNw === sumNe) {
        return 'Draw!';
    } else {
        return sumNw > sumNe ? 'Principal Diagonal win!' : 'Secondary Diagonal win!';
    }
}

The question and answer are referred from https://www.codewars.com/kata/5a8c1b06fd5777d4c00000dd