Submission #286489

#TimeUsernameProblemLanguageResultExecution timeMemory
286489YJUPort Facility (JOI17_port_facility)C++14
0 / 100
33 ms47352 KiB
#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
const ll MOD=1e9+7;
const ll MOD2=998244353;
const ll N=2e6+5;
const ld pi=3.14159265359;
const ll INF=(1LL<<60);
#define SQ(i) ((i)*(i))
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define setp setprecision
#define lwb lower_bound
#define SZ(_a) (ll)_a.size()

set<ll> ck[3],idx;
ll n,x[N],y[N],g[N],col[N],ans=1;
vector<pair<pll,ll> > ed;
vector<ll> v[N];
set<pll> s;

void DFS(ll nd,ll pa){
	for(auto i:v[nd]){
		if(i==pa)continue;
		col[i]=3-col[nd];
		DFS(i,nd);
	}
}

ll F(ll l,ll r){
	auto t=s.lwb(mp(l,0));
	if(t==s.end()||t->X>r)return 0;
	return t->Y;
}
 
int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);
	cin>>n;
	REP1(i,n){
		cin>>x[i]>>y[i];
		ed.pb(mp(mp(x[i],y[i]),i));
	}
	sort(ed.begin(),ed.end());
	for(auto i:ed){
		ll id=F(i.X.X,i.X.Y);
		//cout<<i.X.X<<" "<<i.X.Y<<" "<<id<<"\n";
		s.insert(mp(i.X.Y,i.Y));
		if(!id)continue;
		v[id].pb(i.Y);v[i.Y].pb(id);
	}
	REP1(i,n){
		if(!col[i]){
			ans=ans*2%MOD;
			col[i]=1;
			DFS(i,0);
		}
	}
	for(auto i:ed){
		int ty=col[i.Y];
		if(ck[ty].lwb(i.X.X)!=ck[ty].end()&&*ck[ty].lwb(i.X.X)<i.X.Y){
			cout<<"0\n";return 0;
		}
		ck[ty].insert(i.X.Y);
	}
	cout<<ans<<"\n";
	return 0;
}
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