题解 | #岛屿数量#

using System;
using System.Collections.Generic;


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
     */
    public int solve (List<List<char>> grid) {
        int res = 0;
        for(int i = 0; i < grid.Count; i++){
            for(int j = 0; j < grid[0].Count; j++){
                if(grid[i][j] == '1'){
                    res++;
                    grid[i][j] = '0';
                    dfs(grid, i, j);
                }
            }
        }
        return res;
    }
    public void dfs(List<List<char>> grid, int i, int j){
        if(i > 0 && grid[i - 1][j] == '1'){
            grid[i-1][j] = '0';
            dfs(grid, i-1, j);
        }
        if(j > 0 && grid[i][j - 1] == '1'){
            grid[i][j-1] = '0';
            dfs(grid, i, j-1);
        }
        if(i < grid.Count - 1 && grid[i + 1][j] == '1'){
            grid[i+1][j] = '0';
            dfs(grid, i+1, j);
        }
        if(j < grid[0].Count - 1 && grid[i][j + 1] == '1'){
            grid[i][j+1] = '0';
            dfs(grid, i, j+1);
        }
    }
}