Diagonal Traverse

Given a matrix of M x N elements (M rows, N columns), return all elements of the matrix in diagonal order as shown in the below image.

Example:

Input:
[
 [ 1, 2, 3 ],
 [ 4, 5, 6 ],
 [ 7, 8, 9 ]
]
Output:  [1,2,4,7,5,3,6,8,9]
Explanation:

 

Note:

  1. The total number of elements of the given matrix will not exceed 10,000.

 

 1 public class Solution {
 2     public int[] findDiagonalOrder(int[][] matrix) {
 3         if (matrix.length == 0 || matrix[0].length == 0)
 4             return new int[0];
 5         
 6         int m = matrix.length, n = matrix[0].length, N = m * n;
 7         int[] result = new int[N];
 8         int i = 0, j = 0, index = 0, time = 1;
 9         while (index < N && i < m && j < n) {
10             if (time == 1) {
11                 while(i >= 0 && j < n) {
12                     result[index++] = matrix[i][j];
13                     
14                     i -= 1;
15                     j += 1;
16                     
17                     if (j == n) 
18                         i += 2;
19                 }
20                 i = Math.max(0, i);
21                 j = Math.min(n - 1, j);
22                 
23                 time = 2;
24             } else {
25                 while (i < m && j >= 0) {
26                     result[index++] = matrix[i][j];
27                     i += 1;
28                     j -= 1;
29                     
30                     if (i == m)
31                         j += 2;
32                 }
33                 i = Math.min(m - 1, i);
34                 j = Math.max(0, j);
35                 
36                 time = 1;
37             }
38         }
39         return result;
40     }
41 }

 

posted @ 2017-02-24 20:01  amazingzoe  阅读(204)  评论(0)  编辑  收藏  举报