[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?

 

每次转换四个点。

class Solution {
public:
    void rotate(vector<vector<int>>& matrix) {
        if(matrix.size()<=1) return;
        int n = matrix.size();
        for(int i=0;i<n;i++)
        {
            for(int j=i;j<n-1-i;j++)
            {
                int temp = matrix[i][j];
                matrix[i][j] = matrix[n-1-j][i];
                matrix[n-1-j][i] = matrix[n-1-i][n-1-j];
                matrix[n-1-i][n-1-j] = matrix[j][n-1-i];
                matrix[j][n-1-i] = temp;
            }
        }
        return;
    }
};