【题目】

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?

【analyze】

1.先对角线旋转

2.再左右对调

【算法】

public class Solution {    public void rotate(int[][] matrix) {        int r=matrix.length;        int c=matrix[0].length;        //按主对角线翻转矩阵        for(int i=0;i