求调！！！玄关

#include<bits/stdc++.h>
using namespace std;
int t;
int n;
int f;
int _x[]={1,-1,0,0};
int _y[]={0,0,1,-1};
struct node
{
	int x,y;
}q[100086];
int a[105][105];
bool vis1[105][105],vis2[105][105];
void bfs()
{
	int h=1,t=0;
	memset(q,0,sizeof(q));
	q[++t].x=1;
	q[t].y=1;
	while(h<=t)
	{
		for(int i=0;i<4;i++)
		{
			int dx=q[h].x+_x[i];
			int dy=q[h].y+_y[i];
			if(dx>0&&dx<=n&&dy>0&&dy<=n&&vis1[dx][dy]==0)
			{
				q[++t].x=dx;
				q[t].y=dy;
				vis1[dx][dy]=1;
				if(dx==n&&dy==n)	return ;
			}
		}
		h++;
	}
}
int main()
{
	cin>>t;
	while(t--)
	{
		memset(vis1,0,sizeof(vis1));
		memset(vis2,0,sizeof(vis2));
		f=0;
		cin>>n;
		int z,r;
		for(int i=1;i<=2*n-2;i++)
		{
			cin>>z>>r;
			vis2[z][r]=1;
		}
		bfs();
		for(int i=1;i<=n;i++)
		{
			for(int j=1;j<=n;j++)
			{
				if(vis1[i][j]==1&&vis2[i][j]==0)	f=1;
			}
		}
		if(f==1)	cout<<"Yes"<<endl;
		else	cout<<"No"<<endl;
	}
	
	return 0;
 }