Submission #908763

#	Time	Username	Problem	Language	Result	Execution time	Memory
908763		amirhoseinfar1385	Amusement Park (CEOI19_amusementpark)	C++17	63 / 100	52 ms	16112 KiB

amusementpark

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#include<bits/stdc++.h>
using namespace std;
const int maxn=18,maxm=387420489,mod=998244353;
int pd[maxm],t[(1<<maxn)],mar;
long long mypow(long long m,long long y){
    if(y==0){
        return 1;
    }
    long long p=mypow(m,(y>>1));
    p*=p;
    p%=mod;
    if(y&1){
        p*=m;
        p%=mod;
    }
    return p;
}

int ww(int a){
	if(a>=mod){
		a-=mod;
	}
	return a;
}

pair<int,int>tab2(int a){
	int now=0;
	pair<int,int>ret=make_pair(0,0);
	while(a!=0){
		if(a%3==1){
			ret.first+=(1<<now);
		}else if(a%3==2){
			ret.second+=(1<<now);
		}
		now++;
		a/=3;
	}
	return ret;
}

int back3(int a,int b){
	int ret=t[a]+2*t[b];
	return ret;
}
vector<int>tartib[maxn];
int adj[maxn],adja[maxn];
int n,m;

void aval(){
	mar=(1<<n)-1;
	int nx=1;
	for(int i=0;i<(1<<n);i++){
		int now=1,ret=0;
		for(int j=0;j<n;j++){
			if((i>>j)&1){
				ret+=now;
			}
			now*=3;
		}
		t[i]=ret;
		tartib[__builtin_popcount(i)].push_back(i);
	}
}

void solve(){
	for(int i=0;i<maxn;i++){
		for(auto xx:tartib[i]){
			for(int y=(mar^xx);y>0;y=(y-1)&(mar^xx)){
			int x=back3(xx,y);
			if(pd[x]==0){
				continue;
			}
			pair<int,int>now=make_pair(xx,y);
			for(int j=0;j<n;j++){
				if((now.second>>j)&1){
					now.second^=(1<<j);
					pair<int,int>fake=now;
					fake.first|=(1<<j);
					fake.second|=(adj[j]^(adj[j]&now.first));
					int tof=back3(fake.first,fake.second);
					pd[tof]+=pd[x];
					pd[tof]=ww(pd[tof]);
				}
			}
			}
		}
	}
}

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m;
	aval();	
	for(int i=0;i<m;i++){
		int u,v;
		cin>>u>>v;
		u--;
		v--;
		adj[u]|=(1<<v);
		adj[v]|=(1<<u);
		adja[u]|=(1<<v);
	}
	pd[back3(0,(1<<n)-1)]=1;
	solve();
	int res=back3((1<<n)-1,0);
	pd[res]=1ll*pd[res]*m%mod;
	pd[res]=1ll*pd[res]*mypow(2,mod-2)%mod;
	cout<<pd[res]<<"\n";
}

Compilation message (stderr)

amusementpark.cpp: In function 'void aval()':
amusementpark.cpp:53:6: warning: unused variable 'nx' [-Wunused-variable]
   53 |  int nx=1;
      |      ^~

• Subtask 1: 7 / 7
• Subtask 2: 12 / 12
• Subtask 3: 23 / 23
• Subtask 4: 21 / 21
• Subtask 5: 0 / 37