Submission #1225860

#	Time	Username	Problem	Language	Result	Execution time	Memory
1225860		_rain_	Port Facility (JOI17_port_facility)	C++20	22 / 100	50 ms	44616 KiB

port_facility

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;

const int MOD=1e9+7;
const int N=(int)5e5;
	int mul(int a,int b){
		return (LL)a*b%MOD;
	}

int n;
pair<int,int>p[N+2];

namespace subtask1{
	bool check(){
		return n<=2000;
	}
	
	bool intersec(pair<int,int>x,pair<int,int>y){
		if (x.second<y.first || y.second<x.first) return false;
		if (x.first<=y.first && y.second<=x.second) return false;
		if (y.first<=x.first && x.second<=y.second) return false;
		return true;
	}
	
	vector<int>ke[N+2];
	vector<int>order;
	bool vis[N+2]={};
	
	void dfs(int u){
		vis[u]=true;
		order.push_back(u);
		for(auto&v:ke[u]){
			if (vis[v]==false) {
				dfs(v);
			}
		}
		return;
	}
	
	bool process(){
		vector<pair<int,int>>a[2];
		for(auto&x:order){
			// case 1
				if (a[1].size()==0) a[1].push_back(p[x]);
				else {
					bool can=false;
					for(auto&e:a[1]) can|=intersec(p[x],e);
					if (can){
						for(auto&e:a[0]) if (intersec(p[x],e)) return false;
						a[0].push_back(p[x]);
					}
					else a[1].push_back(p[x]);
				}
		}
		return true;
	}
	
	void main_code(){
		for(int i=1;i<=n;++i){
			for(int j=1;j<=n;++j){
				if (intersec(p[i],p[j])) {
					ke[i].push_back(j);
					ke[j].push_back(i);
				}
			}
		}
		int ans=1;
		for(int i=1;i<=n;++i){
			if (vis[i]==false){
				order.clear();
				dfs(i);
				if (process()==false){
					cout<<0;
					return;
				}
				ans=mul(ans,2);
			}
		}
		cout<<ans;
	}
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0) ; cout.tie(0);
	#define task "main"
	if (fopen(task".inp","r")){
		freopen(task".inp","r",stdin);
		freopen(task".out","w",stdout);
	}
	
	cin>>n;
	for(int i=1;i<=n;++i) cin>>p[i].first>>p[i].second;
	if (subtask1::check()) {
		return subtask1::main_code(),0;
	}
	return 0;
}

Compilation message (stderr)

port_facility.cpp: In function 'int main()':
port_facility.cpp:89:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |                 freopen(task".inp","r",stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
port_facility.cpp:90:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   90 |                 freopen(task".out","w",stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 0 / 56
• Subtask 4: 0 / 22