Leetcode48. Rotate Image

题目---数组操作

You are given an n x n 2D matrix representing an image.
Rotate the image by 90 degrees (clockwise).
Note:
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.

Example 1:
Given input matrix =
[
[1,2,3],
[4,5,6],
[7,8,9]
],
rotate the input matrix in-place such that it becomes:
[
[7,4,1],
[8,5,2],
[9,6,3]
]

题目的大意是对数组在原空间 (不能开另一个数组)上进行顺时针90°旋转
解法分两步就可以实现90°旋转（看图自己比划一下）：
1. 先对数组进行转置
2. 对数组左右对称交换

image.png

代码贴上

class Solution {
    public void rotate(int[][] matrix) {
        transpose(matrix);
        swapLeftRight(matrix);
    }
   // 矩阵转置函数 
    public void transpose(int[][] matrix){
        for(int i=0;i