求大神指点一下关于简单dfs问题

#include<iostream>
#include<stdlib.h>
#include<string.h>
#include<stdio.h>
using namespace std;
int flag;
char f[3][103];
int visited[3][103];
int hang[4]={0,0,-1,1};
int lie[4]={1,-1,0,0};
int n;
void dfs(int h,int l)
{
    visited[h][l]=1;
    int i;
    for(i=0;i<=3;i++)
    {
        int h1=h+hang[i];
        int l1=l+lie[i];
        if(h1>=1&&h1<=2&&l1>=1&&l1<=n)
        {
            if(h1==1&&l1==n)
            {
                flag=1;
                return ;
            }
            else
            {
                if(f[h1][l1]=='.'&&visited[h1][l1]==0)
                {
                    dfs(h1,l1);
                }
            }
        }
    }
    visited[h][l]=0;
}
void shuchu();
int main()
{
    int zong ;
    cin>>zong;
    while(zong--)
    {
        int i,j;
        flag=0;
        for(i=0;i<=2;i++)
            for(j=0;j<=n;j++)
            f[i][j]='W';
        memset(visited,0,sizeof(visited));
        cin>>n;
        for(i=1;i<=2;i++)
        {
            for(j=1;j<=n;j++)
                cin>>f[i][j];
            fflush(stdin);
        }
        //shuchu();
        dfs(1,1);
        if(flag==1)cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }
    return 0;
}
void shuchu()
{
    int i,j;
    for(i=1;i<=2;i++)
    {
        for(j=1;j<=n;j++)
            cout<<f[i][j];
        cout<<endl;
    }
}