#include<bits/stdc++.h>
#define ll long long
const int N=1000007;
const int M=1145141;
using namespace std;
int lsh[M<<1];
int lsh2[M<<1];
int f[M<<1];
int find(int x)
{
	if(x!=f[x])
		f[x]=find(f[x]);
	return f[x];
}
void unionn(int x,int y)
{
	int fx=find(x),fy=find(y);
	f[fx]=fy;
}
int t;
int n;
struct node{
	int a,b,e;
}KOBE[1145141<<1];
bool cmp(node a,node b)
{
	return a.e>b.e;
}
int main(){
	ios::sync_with_stdio(0);
	cin>>t;
	while(t--)
	{
		memset(lsh,0,sizeof(lsh));
		memset(lsh2,0,sizeof(lsh2));
		memset(f,0,sizeof(f));
		
		cin>>n;
		for(int i=1;i<=n;i++) f[i]=i;
		for(int i=1;i<=n;i++)
		{
			cin>>KOBE[i].a>>KOBE[i].b>>KOBE[i].e;
			lsh[i]=KOBE[i].a;lsh2[i]=KOBE[i].b;
		}
		sort(lsh+1,lsh+1+n);
		sort(lsh2+1,lsh2+1+n);
		int t=unique(lsh+1,lsh+1+n)-lsh-1;
		int t2=unique(lsh2+1,lsh2+1+n)-lsh2-1;
		sort(KOBE+1,KOBE+1+n,cmp);
		for(int i=1;i<=n;i++)
		{
			KOBE[i].a=lower_bound(lsh+1,lsh+1+t,KOBE[i].a)-lsh;
			KOBE[i].b=lower_bound(lsh2+1,lsh2+1+t2,KOBE[i].b)-lsh2;
		}
		bool flag=false;
		for(int i=1;i<=n;i++)
		{
			unionn(KOBE[i].a,KOBE[i].b);
			if(KOBE[i].e==0){
				if((find(KOBE[i].a)==find(KOBE[i].b))){
					flag=true;
				}			
			} 
		}
		if(flag==false) cout<<"YES"<<'\n';
		else cout<<"NO"<<'\n'; 
	}

	return 0;
}

cpp #include<bits/stdc++.h> #define ll long long const int N=1000007; const int M=1145141; using namespace std; int lsh[M<<1]; int lsh2[M<<1]; int f[M<<1]; int find(int x) { if(x!=f[x]) f[x]=find(f[x]); return f[x]; } void unionn(int x,int y) { int fx=find(x),fy=find(y); f[fx]=fy; } int t; int n; struct node{ int a,b,e; }KOBE[1145141<<1]; bool cmp(node a,node b) { return a.e>b.e; } int main(){ ios::sync_with_stdio(0); cin>>t; while(t--) { memset(lsh,0,sizeof(lsh)); memset(lsh2,0,sizeof(lsh2)); memset(f,0,sizeof(f));

	cin>>n;
	for(int i=1;i<=n;i++) f[i]=i;
	for(int i=1;i<=n;i++)
	{
		cin>>KOBE[i].a>>KOBE[i].b>>KOBE[i].e;
		lsh[i]=KOBE[i].a;lsh2[i]=KOBE[i].b;
	}
	sort(lsh+1,lsh+1+n);
	sort(lsh2+1,lsh2+1+n);
	int t=unique(lsh+1,lsh+1+n)-lsh-1;
	int t2=unique(lsh2+1,lsh2+1+n)-lsh2-1;
	sort(KOBE+1,KOBE+1+n,cmp);
	for(int i=1;i<=n;i++)
	{
		KOBE[i].a=lower_bound(lsh+1,lsh+1+t,KOBE[i].a)-lsh;
		KOBE[i].b=lower_bound(lsh2+1,lsh2+1+t2,KOBE[i].b)-lsh2;
	}
	bool flag=false;
	for(int i=1;i<=n;i++)
	{
		unionn(KOBE[i].a,KOBE[i].b);
		if(KOBE[i].e==0){
			if((find(KOBE[i].a)==find(KOBE[i].b))){
				flag=true;
			}			
		} 
	}
	if(flag==false) cout<<"YES"<<'\n';
	else cout<<"NO"<<'\n'; 
}

return 0;

} ^