Submission #991885

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Source Code Expand

#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep1(i,n) for(int i=1;i<=(int)(n);i++)
#define all(c) c.begin(),c.end()
#define pb push_back
#define fs first
#define sc second
#define show(x) cout << #x << " = " << x << endl
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
using namespace std;
template<class S,class T> ostream& operator<<(ostream& o,const pair<S,T> &p){return o<<"("<<p.fs<<","<<p.sc<<")";}
template<class T> ostream& operator<<(ostream& o,const vector<T> &vc){o<<"sz = "<<vc.size()<<endl<<"[";for(const T& v:vc) o<<v<<",";o<<"]";return o;}
struct unionfind{
	int par[100000];
	void init(int N){rep(i,N) par[i]=i;}
	int find(int x){
		if(par[x]==x) return x;
		return par[x]=find(par[x]);
	}
	bool same(int x,int y){
		return find(x)==find(y);
	}
	void unite(int x,int y){
		x=find(x),y=find(y);
		if(x==y) return;
		par[y]=x;
	}
}UF;
vector<int> vc[100000];
int main(){
	int N,M;
	cin>>N>>M;
	rep(i,N){
		int K;
		cin>>K;
		int p=0;
		rep(j,K){
			int x;
			cin>>x;
			x--;
			vc[x].pb(i);
		}
	}
	UF.init(N);
	rep(i,M) if(vc[i].size()>0){
		for(int v:vc[i]) UF.unite(v,vc[i][0]);
	}
	int sz=0;
	rep(i,N) if(UF.find(i)==i) sz++;
	if(sz==1) puts("YES");
	else puts("NO");
}

Submission Info

Judge Result