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?

这个for循环中的下标非常容易搞混，一定要区分清楚，到底固定哪一列，对于第二个for里面，i相当于常量，要区分清楚是行变还是列变
并不是i代表行，j代表列

void rotate(vector<vector<int> > &matrix) {int size = matrix.size();if (size < 2) return;for (int i = 0; i < size/2; i++){for (int j = i; j < size-i-1; j++){int temp = matrix[i][j];matrix[i][j] = matrix[size-j-1][i];matrix[size-j-1][i] = matrix[size-i-1][size-j-1];matrix[size-i-1][size-j-1] = matrix[j][size-i-1];matrix[j][size-i-1] = temp;}}        }