0048-rotate-image.js

/**
 * 48. Rotate Image
 * https://leetcode.com/problems/rotate-image/
 * Difficulty: Medium
 *
 * You are given an n x n 2D matrix representing an image, rotate the image by
 * 90 degrees (clockwise).
 *
 * You have to rotate the image in-place, which means you have to modify the input
 * 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.
 */

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

  for (let i = 0; i < matrix.length; i++) {
    for (let j = 0; j < i; j++) {
      [matrix[i][j], matrix[j][i]] = [matrix[j][i], matrix[i][j]];
    }
  }

  return matrix;
};