1 /* 2  * clockwise rotate 3  * first reverse up to down, then swap the symmetry  4  * 1 2 3     7 8 9     7 4 1 5  * 4 5 6  => 4 5 6  => 8 5 2 6  * 7 8 9     1 2 3     9 6 3 7 */ 8 void rotate(vector
     
      
        > &matrix) { 9     reverse(matrix.begin(), matrix.end());10     for (int i = 0; i < matrix.size(); ++i) {11         for (int j = i + 1; j < matrix[i].size(); ++j)12             swap(matrix[i][j], matrix[j][i]);13     }14 }15 16 /*17  * anticlockwise rotate18  * first reverse left to right, then swap the symmetry19  * 1 2 3     3 2 1     3 6 920  * 4 5 6  => 6 5 4  => 2 5 821  * 7 8 9     9 8 7     1 4 722 */23 void anti_rotate(vector
       
        
          > &matrix) {24     for (auto vi : matrix) reverse(vi.begin(), vi.end());25     for (int i = 0; i < matrix.size(); ++i) {26         for (int j = i + 1; j < matrix[i].size(); ++j)27             swap(matrix[i][j], matrix[j][i]);28     }29 }
        
       
      
     

这边有一个可以练习。