Submission #1680105

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Source Code Expand

#include <bits/stdc++.h>
#define REP(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(x) (x).begin(),(x).end()
#define LL long long
#define pii pair<int,int>
#define pll pair<LL,LL>

using namespace std;

int uf[100001];

int root(int x){
    if(uf[x]<0)return x;
    return uf[x]=root(uf[x]);
}

void unite(int x,int y){
    x = root(x);
    y = root(y);

    if(x==y)return;
    if(uf[x]>uf[y])swap(x,y);
    uf[x] += uf[y];
    uf[y] = x;
}

int main(){

    int N,M;cin>>N>>M;
    vector<int> edge[M];
    fill_n(uf,N,-1);
    REP(i,N){
        int K;cin>>K;
        REP(j,K){
            int l;cin>>l;l--;
            edge[l].push_back(i);
        }
    }

    REP(i,M){
        for(int j=0;j<edge[i].size();j++){
            if(j>0)unite(edge[i][j],edge[i][j-1]);
        }

    }


    if(-uf[root(0)]==N)cout<<"YES"<<endl;
    else cout<<"NO"<<endl;

    return 0;
}

Submission Info

Judge Result