就深搜就彳亍了

#include<bits/stdc++.h>
using namespace std;
const int N=1e3+10;
char a[N][N];
int k,n,m,xa,xb,ya,yb,flag;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
void dfs(int x,int y){
	for(int i=0;i<4;i++){
		int nx=x+dx[i];
		int ny=y+dy[i];
		if(nx>0&&nx<=n&&ny>0&&ny<=n&&a[nx][ny]=='.'){
			a[nx][ny]='#';
			if(nx==xb&&ny==yb){
				flag=1;
				return;
			}
			dfs(nx,ny);
		}
	}
}
int main(){
	cin>>k;
	while(k--){
		cin>>n;
		for(int i=1;i<=n;i++){
			for(int j=1;j<=n;j++){
				cin>>a[i][j];
			}
		}
		cin>>xa>>ya>>xb>>yb;
		xa++;
		ya++;
		xb++;
		yb++;
		flag=0;
		dfs(xa,ya);
		if(flag==0)
		    cout<<"NO"<<endl;
		else cout<<"YES"<<endl;
	}
	return 0;
}