(leetcode)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?

使用先对角线翻转，后水平翻转

1      2              对角线翻转      4           2          水平翻转         3          1 

3      4             =========>    3           1       ==========>   4          2

class Solution {
public:
    void rotate(vector<vector<int>>& matrix) {
        int n = matrix.size();
        int temp;
        for(int i = 0;i < n;++i)
        {
            for(int j = 0;j < n-i;++j)
            {
                temp = matrix[i][j];
                matrix[i][j] = matrix[n-j-1][n-i-1];
                matrix[n-j-1][n-i-1] = temp;
            }
        }
        
        for(int i = 0; i < n/2; ++i)//沿着水平线翻转
        {
            for(int j = 0;j < n;++j)
            {
                temp = matrix[i][j];
                matrix[i][j] = matrix[n-i-1][j];
                matrix[n-i-1][j] = temp;
            }
        }
    }
};