题解 | 岛屿数量

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 判断岛屿数量
     * @param grid char字符型二维数组 
     * @return int整型
     */
    int num= 0;
    public void DFS(char[][] grid,int i,int j){
        if(grid[i][j]=='1'){
            grid[i][j]=0;
        }
        int m = grid.length;
        int n = grid[0].length;
        if(i+1<m && grid[i+1][j]=='1'){
            DFS(grid,i+1,j);
        }
        if(i-1>=0 && grid[i-1][j]=='1'){
            DFS(grid,i-1,j);
        }
        if(j+1<n && grid[i][j+1]=='1'){
            DFS(grid,i,j+1);
        }
        if(j-1>=0 && grid[i][j-1]=='1'){
            DFS(grid,i,j-1);
        }
    }
    public int solve (char[][] grid) {
        // write code here
        int m = grid.length;
        int n = grid[0].length;
        for(int i = 0;i<m;i++){
            for(int j = 0;j<n;j++){
                if(grid[i][j] == '1'){
                    DFS(grid,i,j);
                    num++;
                }

            }
        }
        return num;
    }
}