59. Spiral Matrix II java solutions

weixin_30393907

于 2016-06-27 14:00:00 发布

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/guoguolan/p/5620000.html

本文提供了一种使用Java实现的螺旋矩阵生成方法。通过控制四个边界，从外向内一圈一圈地填充数字，最终得到一个n×n的螺旋矩阵。

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

For example,
Given n = 3,

You should return the following matrix:

[
 [ 1, 2, 3 ],
 [ 8, 9, 4 ],
 [ 7, 6, 5 ]
]

 1 public class Solution {
 2     public int[][] generateMatrix(int n) {
 3         int startx = 0,starty = 0,endx = n-1,endy = n-1;
 4         int[][] ans = new int[n][n];
 5         int count = 1;
 6         while(startx <= endx && starty <= endy){
 7             for(int i = startx;i<=endx;i++){
 8                 ans[starty][i] = count++;
 9             }
10             starty++;
11             
12             for(int i = starty;i<=endy;i++){
13                 ans[i][endx] = count++;
14             }
15             endx--;
16             
17             for(int i = endx;i>=startx;i--){
18                 ans[endy][i] = count++;
19             }
20             endy--;
21             
22             for(int i = endy;i>=starty;i--){
23                 ans[i][startx] = count++;
24             }
25             startx++;
26         }
27         return ans;
28     }
29 }