LeetCode 48 旋转图像

https://leetcode-cn.com/problems/rotate-image/
先上下翻转，再主对角线翻转

class Solution {
    public void rotate(int[][] matrix) {
        int n = matrix.length;
        for(int i = 0; i < n / 2; ++i){
            for(int j = 0; j < n; ++j){
                swap(matrix, i, j, n - i - 1, j);
            }
        }
        for(int i = 0; i < n; ++i){
            for(int j = 0; j < i; ++j){
                swap(matrix, i, j, j, i);
            }
        }
    }

    public void swap(int[][] matrix, int x1, int y1, int x2, int y2){
        int t = matrix[x1][y1];
        matrix[x1][y1] = matrix[x2][y2];
        matrix[x2][y2] = t;
    }
}