RotateImage.php

<?php

namespace App;

/**
 * Rotate Image
 *
 * 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.
 *
 * Example 1:
 * Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
 * Output: [[7,4,1],[8,5,2],[9,6,3]]
 *
 * Example 2:
 * Input: matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
 * Output: [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]
 *
 * https://leetcode.com/problems/rotate-image
 */
class RotateImage
{
    /**
     * @param int[][] $matrix
     * @return void
     */
    public function rotate(array &$matrix): void
    {
        $row = count($matrix);
        for ($i = 0; $i < $row; $i++) {
            for ($j = 0; $j <= $i; $j++) {
                $temp = $matrix[$i][$j];
                $matrix[$i][$j] = $matrix[$j][$i];
                $matrix[$j][$i] = $temp;
            }
        }
        for ($i = 0; $i < $row; $i++) {
            $matrix[$i] = array_reverse($matrix[$i]);
        }
    }
}