Submission #992006

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
struct uni{
  int d[100005];
  void init(){ memset(d,-1,sizeof(d));}    
  int find(int a){ return ( d[a]<0?a:(d[a]=find(d[a])) ); }
  void merge(int a,int b){
    a = find(a); b = find(b);
    if( a == b ) return;
    if( d[a] > d[b] ) swap( a, b );
    d[a] += d[b]; d[b] = a;
  }
  int size(int a){ return -d[find(a)]; }    
};
int N,M;
vector<int> L[100005];
uni U;
int main(){
  cin >> N >> M;
  for(int i=0;i<N;i++){
    int k; cin >> k;
    for(int j=0;j<k;j++){
      int l; cin >> l; --l;
      L[l].push_back( i );
    }
  }
  U.init();
  for(int i=0;i<M;i++){
    for( int j=1;j<(int)L[i].size();j++)
      U.merge( L[i][j-1], L[i][j] );
  }
  if( U.size(0) == N ) cout << "YES" << endl;
  else cout << "NO" << endl;
}

Submission Info

Judge Result