Find the difference between the sum of diagonals in a 2D matrix using JavaScript

Question

Find the difference between the sum of diagonals in a 2D matrix using JavaScript

I'm currently practicing on hackerrank and came across a challenge involving a two-dimensional matrix. Unfortunately, I encountered an error in my code implementation.

11 2 4
4 5 6
10 8 -12

The task at hand is to calculate the sum along the primary diagonal: 11 + 5 - 12 = 4, then the secondary diagonal: 4 + 5 + 10 = 19, finally resulting in 19 - 4 = 15.

function diagonalDifference(arr) {
     var sumRight = 0;
     var sumLeft = 0;
     var array = new Array();
     for(var i = 0; i < arr.length ; i++ ){
          for(var j = 0; j < arr[i].length; j++){
               array.push(arr[i][j]);
          }
     }
     for (var i = 0 ; i < array.length; i = i + 4){
          sumRight += array[i];
     }
     for (var j = 2 ; j < array.length - 1 ; j = j + 2 ){
          sumLeft += array[j];
     }
     return sumLeft - sumRight;
}

javascript

Answer 1

Answer №1

give this a shot

function calculateDiagonalSums(matrix) {

    let primarySum = 0, secondarySum = 0;
    for (let row = 0; row < matrix.length; row++) {
        primarySum += matrix[row][row];
        secondarySum += matrix[row][matrix.length - row - 1];
    }
    console.log(primarySum + ' ' + secondarySum);
    console.log(primarySum - secondarySum);
}

calculateDiagonalSums([[11,2,4],[4,5,6],[10,8,-12]]);

Answer 2

give this a shot

function calculateDiagonalSums(matrix) {

    let primarySum = 0, secondarySum = 0;
    for (let row = 0; row < matrix.length; row++) {
        primarySum += matrix[row][row];
        secondarySum += matrix[row][matrix.length - row - 1];
    }
    console.log(primarySum + ' ' + secondarySum);
    console.log(primarySum - secondarySum);
}

calculateDiagonalSums([[11,2,4],[4,5,6],[10,8,-12]]);

Answer 3

Answer №2

It appears that your current approach may not be leading in the right direction. A more effective solution involves calculating the sum of elements from the top-left to bottom-right (referred to as sumRigth). Subsequently, calculate the sum of elements from the top-right to bottom-left (stored as sumLeft). This assumes that the arrays consist of numbers and are of equal size.

function findDiagonalDifference(matrix) {
     let sumRigth = 0, sumLeft = 0, count = 0;
     for (let i = 0 ; i < matrix.length; i++){
          sumRigth += matrix[i][count++];
     }
     count = matrix.length-1;
     for (let i = 0; i < matrix.length; i++){
          sumLeft += matrix[i][count--];
     }
     return sumLeft - sumRigth;
}

let arr = [
     [11, 2, 4],
     [4, 5, 6],
     [10, 8, -12]
];
console.log(findDiagonalDifference(arr));

Answer 4

It appears that your current approach may not be leading in the right direction. A more effective solution involves calculating the sum of elements from the top-left to bottom-right (referred to as sumRigth). Subsequently, calculate the sum of elements from the top-right to bottom-left (stored as sumLeft). This assumes that the arrays consist of numbers and are of equal size.

function findDiagonalDifference(matrix) {
     let sumRigth = 0, sumLeft = 0, count = 0;
     for (let i = 0 ; i < matrix.length; i++){
          sumRigth += matrix[i][count++];
     }
     count = matrix.length-1;
     for (let i = 0; i < matrix.length; i++){
          sumLeft += matrix[i][count--];
     }
     return sumLeft - sumRigth;
}

let arr = [
     [11, 2, 4],
     [4, 5, 6],
     [10, 8, -12]
];
console.log(findDiagonalDifference(arr));

Answer 5

Answer №3

By utilizing a single loop, it is possible to obtain two values directly to use for summation.

function calculateSum(matrix) {
    let total = 0;

    for (let i = 0, length = matrix.length; i < length; i++)
        total += matrix[i][length - i - 1] - matrix[i][i];

    return total;
}

console.log(calculateSum([[11, 2, 4], [4, 5, 6], [10, 8, -12]]));

Answer 6

By utilizing a single loop, it is possible to obtain two values directly to use for summation.

function calculateSum(matrix) {
    let total = 0;

    for (let i = 0, length = matrix.length; i < length; i++)
        total += matrix[i][length - i - 1] - matrix[i][i];

    return total;
}

console.log(calculateSum([[11, 2, 4], [4, 5, 6], [10, 8, -12]]));

Find the difference between the sum of diagonals in a 2D matrix using JavaScript

Answer №1

Answer №2

Answer №3

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