49-Rotate-Image.js

/**
 * @param {number[][]} matrix
 * @return {void} Do not return anything, modify matrix in-place instead.
 */
var rotate = function(matrix) {
    transpose(matrix);
    reflect(matrix);
};

var transpose = function(matrix) {
    let n = matrix.length;
    for (let i = 0; i < n; i++) {
        for (let j = i + 1; j < n; j++) {
            let temp = matrix[j][i];
            matrix[j][i] = matrix[i][j];
            matrix[i][j] = temp;
        }
    }
}

var reflect = function(matrix) {
    let n = matrix.length;
    for (let i = 0; i < n; i++) {
        for (let j = 0; j < n / 2; j++) {
            let temp = matrix[i][j];
            matrix[i][j] = matrix[i][n - j - 1];
            matrix[i][n - j - 1] = temp;
        }
    }
}