题解 | 顺时针旋转矩阵

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param mat int整型二维数组
     * @param n int整型
     * @return int整型二维数组
     */
    public int[][] rotateMatrix (int[][] mat, int n) {
        //先上下翻转
        for (int i = 0; i < n / 2; i++) {
            for (int j = 0; j < n; j++) {
                int tmp = mat[i][j];
                mat[i][j] = mat[n - i - 1][j];
                mat[n - i - 1][j] = tmp;
            }
        }

        //再按对角线翻转
        for (int i = 0; i < n; i++) {
            for (int j = i + 1; j < n; j++) {
                int tmp = mat[i][j];
                mat[i][j] = mat[j][i];
                mat[j][i] = tmp;
            }
        }
        return mat;
    }
}