Problem Description

You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).

You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.

Examples

Example 1:

https://assets.leetcode.com/uploads/2020/08/28/mat1.jpg

Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
Output: [[7,4,1],[8,5,2],[9,6,3]]

Example 2:

https://assets.leetcode.com/uploads/2020/08/28/mat2.jpg

Input: matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
Output: [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]

Constraints:

解析

給定一個矩陣 matrix

要求在不使用其他額外存儲空間下

把 matrix 順時針方向 旋轉 90 度

要求寫出這樣的演算法