200. 岛屿数量

 1 class Solution {
 2     public int numIslands(char[][] grid) {
 3         int count=0;
 4         for(int i=0;i<grid.length;i++){
 5             for(int j=0;j<grid[0].length;j++){
 6                 // 遍历每个节点找出所有得
 7                 if(grid[i][j]==‘1‘){
 8                     bfs(grid,i,j);
 9                     count++;
10                 }          
11             }
12         }
13         return count;
14     }
15 
16     private void bfs(char[][] grid,int i,int j){
17         Queue<int[]> queue = new LinkedList<>();
18         queue.add(new int[]{i,j});
19         while(!queue.isEmpty()){
20             // 取出当前节点位置，并将其相连节点压入队列
21             int[] temp = queue.poll();
22             i = temp[0];
23             j = temp[1];
24             if(0<=i && i<grid.length && 0<=j && j<grid[0].length && grid[i][j]==‘1‘){
25                 grid[i][j]=‘0‘;
26                 queue.add(new int[]{i+1,j});
27                 queue.add(new int[]{i-1,j});
28                 queue.add(new int[]{i,j+1});
29                 queue.add(new int[]{i,j-1});
30             }
31         }
32     }
33 }