Rotate Image

先按照对角线翻转，再按照x轴翻转

public class Solution {
    public void rotate(int[][] matrix) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        int len = matrix.length;
        if(len == 0)
            return;
        
        for(int i = 0; i < len - 1; i++){
            for(int j = 0; j < len -i; j++){
                swap(matrix, i, j, len - 1 - j, len - 1 -i);
            }
        }
        
        
        for(int i = 0; i < len / 2; i++){
            for(int j = 0; j < len; j++){
                swap(matrix, i, j, len - 1 -i, j);
            }
        }
    }
    
    public void swap(int[][] matrix, int i, int j, int m, int n){
        int tmp = matrix[i][j];
        matrix[i][j] = matrix[m][n];
        matrix[m][n] = tmp;
    }
}