题解 | #岛屿数量#

import java.util.*;


public class Solution {
    // 多源dfs
    public int solve (char[][] grid) {
        int ans = 0;
       for(int i = 0; i < grid.length; i++){
           for(int j = 0; j < grid[0].length; j++){
               if(grid[i][j] == '1'){
                   ans++;
                   dfs(grid,i,j);
               }
           }
       }
        return ans;
    }
    
    
    private void dfs(char[][] grid,int x,int y){
        if(x < 0 || x >= grid.length || y < 0 || y >= grid[0].length || grid[x][y] != '1') return;
        grid[x][y] = '2';
        dfs(grid,x+1,y);
        dfs(grid,x-1,y);
        dfs(grid,x,y+1);
        dfs(grid,x,y-1);
    }
}