Submission #995825

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
vector<int>x[200002];
int n,m,p,a,dist[200002];bool OK=true;
int main(){
	cin>>n>>m;
	for(int i=0;i<n;i++){
		cin>>p;for(int j=0;j<p;j++){cin>>a;a--;x[i].push_back(a+n);x[a+n].push_back(i);}
	}
	for(int i=0;i<200002;i++)dist[i]=1000000;dist[0]=1;queue<int>Q;Q.push(0);
	while(!Q.empty()){
		int a1=Q.front();Q.pop();
		for(int i=0;i<x[a1].size();i++){
			if(dist[x[a1][i]]==1000000){
				dist[x[a1][i]]=dist[a1]+1;
				Q.push(x[a1][i]);
			}
		}
	}
	for(int i=0;i<n;i++){if(dist[i]==1000000){cout<<"NO"<<endl;return 0;}}
	cout<<"YES"<<endl;
	return 0;
}

Submission Info

Judge Result