Submission #1799242

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
typedef pair<int,P> P1;
typedef pair<P,P> P2;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-7
#define INF 1000000000
#define mod 1000000007
#define fi first
#define sc second
#define rep(i,x) for(int i=0;i<x;i++)
#define repn(i,x) for(int i=1;i<=x;i++)
#define SORT(x) sort(x.begin(),x.end())
#define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end())
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin())
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin())
int n,m;
int par[100005],ran[100005];
set<int>S;
void init(){ for(int i=0;i<100005;i++) par[i] = i; }
int find(int x){ if(x == par[x]) return x; else return par[x] = find(par[x]); }
void unite(int x,int y){
	x = find(x); y = find(y); if(x==y) return;
	if(ran[x] < ran[y]) par[x] = y;
	else{
		par[y] = x;
		if(ran[x] == ran[y]) ran[x]++;
	}
}
bool same(int x,int y){ return find(x)==find(y); }
int main(){
	cin>>n>>m;
	init();
	rep(i,n){
		int x; cin>>x;
		int pre = -1;
		rep(j,x){
			int a; cin>>a; S.insert(a);
			if(pre != -1){
				unite(pre,a);
			}
			pre = a;
		}
	}
	set<int>SS;
	for(set<int>::iterator it=S.begin();it!=S.end();++it){
		SS.insert(find(*it));
	}
	puts((SS.size()==1?"YES":"NO"));
}

Submission Info

Judge Result