[LeetCode] Rotate Image

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?

解題思路：

題目要求原地算法。假設坐標軸如上所示。順時針旋轉90度，相當於先將圖片沿著x=n/2翻轉，然後再將圖片沿著斜對角線y=x翻轉。代碼如下：

class Solution {
public:
    void rotate(vector>& matrix) {
        int len = matrix.size();
        //先將矩陣左右翻轉
        for(int i = 0; i& v){
        int len = v.size();
        int i=0, j=len-1;
        while(i& v, int i, int j){
        int temp = v[i];
        v[i] = v[j];
        v[j] = temp;
    }
};