Java 图的遍历-LeetCode200

 1 public class Solution {
 2     class pos {
 3         public int x;
 4         public int y;
 5 
 6         public pos(int x, int y) {
 7             this.x = x;
 8             this.y = y;
 9         }
10     }
11 
12     public int numIslands(char[][] grid) {
13         if (grid.length == 0)
14             return 0;
15         int count = 0;
16         int xl = grid.length, yl = grid[0].length;
17         int[][] visit = new int[xl][yl];
18         LinkedList<pos> lp = new LinkedList<Solution.pos>();
19         pos cur;
20         for (int i = 0; i < xl; i++) {
21             for (int j = 0; j < yl; j++) {
22                 if (grid[i][j] == ‘0‘)
23                     continue;
24                 if (grid[i][j] == ‘1‘ && visit[i][j] == 1)
25                     continue;
26                 cur = new pos(i, j);
27                 lp.push(cur);
28                 while (lp.size() > 0) {
29                     cur = lp.poll();
30                     visit[cur.x][cur.y] = 1;
31                     if (cur.x + 1 < xl && grid[cur.x + 1][cur.y] == ‘1‘
32                             && visit[cur.x + 1][cur.y] != 1) {
33                         lp.push(new pos(cur.x + 1, cur.y));
34                     }
35                     if (cur.x - 1 >= 0 && grid[cur.x - 1][cur.y] == ‘1‘
36                             && visit[cur.x - 1][cur.y] != 1) {
37                         lp.push(new pos(cur.x - 1, cur.y));
38                     }
39                     if (cur.y + 1 < yl && grid[cur.x][cur.y + 1] == ‘1‘
40                             && visit[cur.x][cur.y + 1] != 1) {
41                         lp.push(new pos(cur.x, cur.y + 1));
42                     }
43                     if (cur.y - 1 >= 0 && grid[cur.x][cur.y - 1] == ‘1‘
44                             && visit[cur.x][cur.y - 1] != 1) {
45                         lp.push(new pos(cur.x, cur.y - 1));
46                     }
47                 }
48                 ++count;
49             }
50         }
51 
52         return count;
53     }
54 
55     public static void main(String[] args) {
56         char[][] grid1 = { { ‘1‘, ‘1‘, ‘1‘, ‘1‘, ‘0‘ },
57                 { ‘1‘, ‘1‘, ‘0‘, ‘1‘, ‘0‘ }, { ‘1‘, ‘1‘, ‘0‘, ‘0‘, ‘0‘ },
58                 { ‘0‘, ‘0‘, ‘0‘, ‘0‘, ‘0‘ } }, grid2 = {
59                 { ‘1‘, ‘1‘, ‘0‘, ‘0‘, ‘0‘ }, { ‘1‘, ‘1‘, ‘0‘, ‘0‘, ‘0‘ },
60                 { ‘0‘, ‘0‘, ‘1‘, ‘0‘, ‘0‘ }, { ‘0‘, ‘0‘, ‘0‘, ‘1‘, ‘1‘ } }, grid3 = {
61                 { ‘1‘, ‘1‘, ‘1‘ }, { ‘0‘, ‘1‘, ‘0‘ }, { ‘1‘, ‘1‘, ‘1‘ } };
62         Solution s = new Solution();
63         System.out.println(s.numIslands(grid1));
64         System.out.println(s.numIslands(grid2));
65         System.out.println(s.numIslands(grid3));
66     }
67 }