/**
1. 观察下样例: 先按对角线翻转, 然后按行翻转
*/

class Solution {
    public void rotate(int[][] matrix) {
        if (matrix == null || matrix.length == 0 || matrix[0].length == 0) return;
        reverseByDig(matrix);
        reverseByrow(matrix);
    }

    public void reverseByDig(int[][] matrix){
        for (int i = 0 ; i < matrix.length; i++)
            for (int j = 0; j < i ; j++)    
                swap(matrix, i, j, j, i);
    }

    public void reverseByrow(int[][] matrix){
        for (int i = 0; i < matrix.length ; i++)
            for (int l = 0, r = matrix[0].length - 1; l < r; l ++ ,r --) 
                swap(matrix, i, l, i, r);
    }

    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;
    }
}