Rotate Image

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise).

Have you met this question in a real interview? 

Yes

Example

Given a matrix

[
    [1,2],
    [3,4]
]

rotate it by 90 degrees (clockwise), return

[
    [3,1],
    [4,2]
]

Challenge

Do it in-place.

public class Solution {

    /**

     * @param matrix: A list of lists of integers

     * @return: Void

     */

    public void rotate(int[][] matrix) {

        

        // write your code here

        if(matrix == null || matrix.length == 0 || matrix[0].length == 0){

            return;

        }

        int n = matrix.length;

        

        for(int layer = 0; layer < n / 2; layer++){

            for(int i = layer; i < n - 1 - layer; i++){

                int temp = matrix[i][layer];

                matrix[i][layer] = matrix[n-1-layer][i];

                matrix[n-1-layer][i] = matrix[n -1 - i][n-layer-1];

                matrix[n-1-i][n-1-layer] = matrix[layer][n-1-i];

                matrix[layer][n-1-i] = temp;

            }

        }

    }

}