codevs1215 迷宫

用dfs做的，还不嫌累的用if，当然bfs也很好做（代码很丑）。

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
using namespace std;
int n;
bool flag;
bool vis[50][50];
char s[50][50];
void dfs(int x,int y)
{
    if(x == n&&y == n)
    {
        flag = 1;
        return ;
    }
    vis[x][y] = 1;
    if(s[x+1][y] == '.'&&!vis[x+1][y])
    {
        vis[x+1][y]=1;
        dfs(x+1,y);
    }
    if(s[x-1][y] == '.'&&!vis[x-1][y])
    {
        vis[x-1][y]=1;
        dfs(x-1,y);
    }
    if(s[x][y+1] == '.'&&!vis[x][y+1])
    {
        vis[x][y+1]=1;
        dfs(x,y+1);
    }
    if(s[x][y-1] == '.'&&!vis[x][y-1])
    {
        vis[x][y-1]=1;
        dfs(x,y-1);
    }
}
int main()
{
    int t;
    cin>>t;
    for(int k = 1; k <= t; k ++)
    {
        flag = 0;
        memset(vis,0,sizeof(vis));
        cin>>n;
        for(int i = 1; i <= n; i ++)
        for(int j = 1; j <= n; j ++)
        {
            cin>>s[i][j];
        }
        for(int i = 1; i <= n; i ++)
        for(int j = 1; j <= n; j ++)
        {
            if(s[i][j] == 's'||s[i][j] == 'e')
            {
                s[i][j] ='.';
            }
        }
        dfs(1,1);
        if(flag)
        puts("YES");
        else
        puts("NO");
    }
    return 0;
}