题解 | #顺时针旋转矩阵#

import java.util.*;
//经过分析可以得知矩阵经过两步就可以旋转90度
//1.先进性上下翻转
//2.再进行置换
public class Solution {
    public int[][] rotateMatrix(int[][] mat, int n) {
        // write code here
        int top = 0;
        int tail = n - 1;
        for (; top < tail; top++, tail--){  //先进性上下翻转
            for (int i = 0; i < n; i++){
                mat[top][i] = mat[top][i] ^ mat[tail][i];
                mat[tail][i] = mat[top][i] ^ mat[tail][i];
                mat[top][i] = mat[top][i] ^ mat[tail][i];
            }
        }
        for (int i = 0; i < n; i++){
            for (int j = n - 1; j > i; j--){
                mat[i][j] = mat[i][j] ^ mat[j][i];
                mat[j][i] = mat[i][j] ^ mat[j][i];
                mat[i][j] = mat[i][j] ^ mat[j][i];
            }
        }
        return mat;
    }
}