[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?

Do not think too much about this problem, don't be scared by the "Matrix" word. This problem can be done in an easy way.
like the picture below:
origin:rotate:

you can read as the 1st picture, and put it on a new one with a different order.

 class Solution {
 public:
     void rotate(vector<vector<int> > &matrix) {
         auto result = matrix;
         for (int j=; j<matrix.size(); j++){
             for (int i=; i<matrix.size(); i++){
                 result[j][matrix.size()-i-] = matrix[i][j];
             }
         }
         matrix = result;
     }
 };

this is a naive one, it take extra space to rotate, there are some smarter way which can do in-place transposition. I'll check that later.