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Diagonal Difference | Solution | JavaScript
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/* | |
Diagonal Difference Solution. | |
sample matrix = [[1,2,3], [4,5,6], [7,8,9]] | |
*/ | |
function diagonalDifference(matrix) { | |
// length of input matrix. | |
const length = matrix.length; | |
let diagonal1 = 0, diagonal2 = 0; | |
// Looping through the array and summing the diagonals. | |
for(let i = 0; i < length; i++){ | |
// Calculating the primary diagonal. | |
diagonal1 += matrix[i][i]; | |
// Reversing the second dimension of array to calculate secondary diagonal. | |
diagonal2 += matrix[length -1 - i][i] | |
} | |
// return absolute difference value. | |
return Math.abs(diagonal1 - diagonal2); | |
} |
metaory
commented
Jun 21, 2022
function diagonalDifference(arr) {
let n = arr.length - 1
// caluclate the difference in every row
// e.g. first row: first - last element, second row: secondElement - (secondLast element)
arr = arr.map((el,i) => el[i]-el[n-i]).reduce((p,c)=>p+c)
return Math.abs(arr)
}
Alternative solution, just use the same For loop, to loop through in ascending and descending order:
function diagonalDifference(arr) { // Write your code here let firstDiagonalTotal = 0 let secondDiagonalTotal = 0 // firstDiagonal = arr[0][0] + arr[1][1] + arr[2][2] // secondDiagonal = arr[0][2] + arr[1][1] + arr[2][0] for (let i = 0, k = arr[0].length - 1; i < arr[0].length; i++, k--) { firstDiagonalTotal += arr[i][i] secondDiagonalTotal += arr[i][k] } return Math.abs(firstDiagonalTotal - secondDiagonalTotal) }
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