我的错误代码：

#include<bits/stdc++.h>
using namespace std;
int n;
string a[1001];
int b,c,d,e;
bool g;
int dfs(int x,int y){
	if(x<0 or x>n or y<0 or y>n or a[x][y]=='#') return 0;
	if(x==d and y==e) g=true;
	a[x][y]='#';
	dfs(x-1,y);
	dfs(x+1,y);
	dfs(x,y-1);
	dfs(x,y+1);
}
int main(){
	int k;
	cin>>k;
	for(int i=0;i<k;i++){
		g=false;
		cin>>n;
		for(int x=0;x<n;x++){
			cin>>a[x];
		}
		cin>>b>>c>>d>>e;
		if(a[b][c]=='#' or a[e][d]=='#'){
			cout<<"NO"<<endl;
			goto f;
		}
		dfs(b,c);
		if(g==1)cout<<"YES"<<endl;
		else cout<<"NO"<<endl;
		f:{}
	}
	return 0;
}

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