90 degree rotation matrix

First symmetrical reversal, then fold, remember that interview on the line along the right diagonal

Code:

 1 class Solution {
 2 public:
 3     void rotate(vector<vector<int>>& matrix) {
 4         int len = matrix.size();
 5         //左右翻
 6         for(int i=0;i<len;i++){
 7             for(int j=0;j<len/2;j++){
 8                 int temp = matrix[i][j];
 9                 matrix[i][j] = matrix[i][len-1-j];
10                 matrix[i][len-1-j] = temp;
11             }
12         }
13         //对角线翻转
14         for(int i=0;i<len;i++){
15             for(int j=0;j<len-i;j++){
16                 int temp = matrix[i][j];
17                 matrix[i][j] = matrix[len-1-j][len-1-i];
18                 matrix[len-1-j][len-1-i] = temp;
19             }
20         }
21     }
22 };