[Leetcode]-- Rotate Image

 1 public class Solution {
 2    public void rotate(int[][] matrix) {
 3         int len = matrix.length;
 4         if(len == 0)
 5             return;
 6         
 7         for(int i = 0; i < len - 1; i++){
 8             for(int j = 0; j < len -i; j++){
 9                 swap(matrix, i, j, len - 1 - j, len - 1 -i);
10             }
11         }
12         
13         
14         for(int i = 0; i < len / 2; i++){
15             for(int j = 0; j < len; j++){
16                 swap(matrix, i, j, len - 1 -i, j);
17             }
18         }
19     }
20     
21     public void swap(int[][] matrix, int i, int j, int m, int n){
22         int tmp = matrix[i][j];
23         matrix[i][j] = matrix[m][n];
24         matrix[m][n] = tmp;
25     }
26 }