題目：

解答：

外圈向內圈逐步旋轉

程式碼：

class Solution {
public:
    void rotate(vector<vector<int> > &matrix) {
        int len = matrix.size();
        if( len == 1 || len == 0 )  return;
        for( int i = 0;2 * i + 1 < len;++i )    {
            int row = i, col = i, maxcol = len - i - 1;
            for
 
(;col < maxcol;++col )  {
                int temp = matrix[row][col];
                matrix[row][col] = matrix[len - col - 1][row];
                matrix[len - col - 1][row] = matrix[len - row - 1][len - col - 1];
                matrix[len - row - 1][len - col - 1] = matrix[col][len - row - 1
 
];
                matrix[col][len - row - 1] = temp;
            }
        }
    }
};