Submission #1066674

#	Time	Username	Problem	Language	Result	Execution time	Memory
1066674		vjudge1	Amusement Park (CEOI19_amusementpark)	C++17	42 / 100	11 ms	604 KiB

amusementpark

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
bitset<1<<18>indep;
ll dp[1<<18];
const int mod=1e9+7;
int EDG[20][20];
int main(){
    int n,m;
    cin>>n>>m;
    for(int i=0;i<m;i++){
        int a,b;
        cin>>a>>b;
        EDG[a][b]=1;
    }
    for(int i=1;i<1<<n;i++){
        vector<int>v;
        for(int j=0;j<n;j++)
            if(i&1<<j)
                v.push_back(j+1);
        int bad=0;
        for(auto i:v)
            for(auto j:v)
                if(EDG[i][j])
                    bad=1;
        indep[i]=!bad;
    }
    dp[0]=1;
    for(int i=1;i<1<<n;i++)
        for(int j=i;j;j=j-1&i){
            if(!indep[j])continue;
            int cnt=__builtin_popcount(j);
            dp[i]=(dp[i]+dp[i^j]*(cnt&1?1:-1))%mod;
        }
    cout<<dp[(1<<n)-1]*m%mod*(ll)(5e8+4)%mod<<'\n';
}

Compilation message (stderr)

amusementpark.cpp: In function 'int main()':
amusementpark.cpp:30:26: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   30 |         for(int j=i;j;j=j-1&i){
      |                         ~^~

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