LeetCode 048 Rotate Image

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]);

    }
};