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?
对应的4个点，依次互换位置。
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?
对应的4个点，依次互换位置。