Submission #955857

#	Time	Username	Problem	Language	Result	Execution time	Memory
955857		Trisanu_Das	Amusement Park (CEOI19_amusementpark)	C++17	100 / 100	2894 ms	4728 KiB

amusementpark

#include <bits/stdc++.h>
#define mod 998244353ll
#define LL long long
#define LD long double
#define MP make_pair
#define PB push_back
#define all(v) v.begin(),v.end()
using namespace std;
 
LL binpow(LL a,int n) {
	if(n==0) return 1;
	if(n%2==0) return binpow(a*a%mod,n/2);
	return a*binpow(a,n-1)%mod;
}
 
bool inMask(int a,int mask) {
	return (bool)((1<<a)&mask);
}
 
int n,m;
int ans[(1<<18)+10],cnt[(1<<18)+10];
vector<pair<int,int>> p;
vector<int> g[20];
bool isEdge[(1<<18)+10];
int main()
{
	cin>>n>>m;
	for(int i=1;i<=m;i++)
	{
		int a,b;
		cin>>a>>b;
		a--;
		b--;
		g[a].PB(b);
		g[b].PB(a);
		p.PB(MP(a,b));
	}
 
	for(int mask=0;mask<(1<<n);mask++)
	{
		for(int i=0;i<n;i++)
		{
			if(((1<<i)&mask)==0)
				continue;
			cnt[mask]++;
			for(int j=0;j<g[i].size();j++)
				isEdge[mask]|=inMask(g[i][j],mask);
		}
	}
	ans[0]=1;
	for(int mask=1;mask<(1<<n);mask++) {
		int s=mask;
		vector<int> S;
		while(s){
			S.PB(s);
			s=(s-1)&mask;
		}
 
		while(!S.empty()) {
			s=S.back();
			S.pop_back();
			if(isEdge[s])
				continue;
			if(cnt[s]%2==1)
				ans[mask]+=ans[mask^s];
			else
				ans[mask]+=mod-ans[mask^s];
			ans[mask]%=mod;
		}
	}
 
	LL answ=ans[(1<<n)-1];
	answ*=(LL)m;
	answ%=mod;
	answ*=binpow(2,mod-2);
	answ%=mod;
 
	cout<<answ<<endl;
 
	return 0;
}

Compilation message (stderr)

amusementpark.cpp: In function 'int main()':
amusementpark.cpp:46:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |    for(int j=0;j<g[i].size();j++)
      |                ~^~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 12 / 12
• Subtask 3: 23 / 23
• Subtask 4: 21 / 21
• Subtask 5: 37 / 37