题目要求：Rotate Image
You are given an n x n 2D matrix representing an image.
Rotate the image by 90 degrees (clockwise).
Follow up:
Could you do this in-place?
代码如下：
class Solution { public: void rotate(vector<vector<int> > &matrix) { const int n = matrix.size(); for(int i = 0; i < n; i++) //沿着副对角线反转 for(int j = 0; j < n - i; j++) swap(matrix[i][j], matrix[n - 1 - j][n - 1 - i]); for(int i = 0; i < n / 2; i++)//沿着水平中线反转 for(int j = 0; j < n; j++) swap(matrix[i][j], matrix[n - 1 - i][j]); } };
原文：http://www.cnblogs.com/510602159-Yano/p/4279321.html