Submission #748192

#	Time	Username	Problem	Language	Result	Execution time	Memory
748192		PVSekhar	Amusement Park (CEOI19_amusementpark)	C++14	100 / 100	2380 ms	4436 KiB

amusementpark

#include <bits/stdc++.h>
using namespace std;
#define ll long long
// const ll MOD = 1e9+7;
const ll MOD = 998244353;
const ll N=18;
const ll inv=499122177;
int edges[N+1];
ll ans[(1<<N)+1];
int cnt[(1<<N)+1];//parity of number of bits
int ind[(1<<N)+1];//independence of nodes in set

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    for(int i=0;i<=N;i++)edges[i]=0;
    for(int i=0;i<=(1<<N);i++)ans[i]=0;
    for(int i=0;i<=(1<<N);i++)cnt[i]=0;
    for(int i=0;i<=(1<<N);i++)ind[i]=0;

    int n,m,a,b;
    cin>>n>>m;
    for (int i = 0; i < m; i++)
    {
        cin>>a>>b;
        a--;
        b--;
        edges[a]+=(1<<b);
        edges[b]+=(1<<a);
    }
    for (int i = 0; i < (1<<n); i++)
    {
        int check=1,num=0;
        for (int k = 0; k < n; k++)
        {
            if((i^(1<<k))<i){
                if((edges[k]&i))check=0;
            }
            if(!check)break;
        }
        ind[i]=check;
        for (int k = 0; k < n; k++)if((i^(1<<k))<i)cnt[i]++;
        cnt[i]%=2;
    }
    
    ans[0]=1;
    for (int i = 1; i < (1<<n); i++)
    {
        for (int j = i; j > 0; j=((j-1)&i))
        {
            if(!ind[j])continue;
            // cout<<i<<" "<<j<<" "<<cnt<<"\n";
            if(cnt[j]){
                ans[i]+=ans[i^j];
            }else{
                ans[i]-=ans[i^j];
                ans[i]+=MOD;
            }
            ans[i]%=MOD;
        }
    }
    cout<<(((ans[(1<<n)-1]*m)%MOD)*inv)%MOD<<"\n";
    return 0;   
}

Compilation message (stderr)

amusementpark.cpp: In function 'int main()':
amusementpark.cpp:34:21: warning: unused variable 'num' [-Wunused-variable]
   34 |         int check=1,num=0;
      |                     ^~~

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