HDU5036 Explosion(期望&&bitset)

 

#include <iostream>

#include <cstring>

#include <string>

#include <vector>

#include <cstdio>

#include <algorithm>

#include <cmath>

#include <bitset>

using namespace std;



#define maxn 1005



bitset<1100> b[maxn];

int n;



int main()

{

    int T;cin>>T;int ca=0;

    while(T--){

        scanf("%d",&n);

        for(int i=1;i<=n;++i) b[i].reset();

        for(int i=1;i<=n;++i){

            int num;scanf("%d",&num);

            b[i][i]=true;

            while(num--){

                int tmp;

                scanf("%d",&tmp);

                b[i][tmp]=true;

            }

        }

        for(int i=1;i<=n;++i){

            for(int j=1;j<=n;++j){

                if(b[j][i]) b[j]|=b[i];

            }

        }

        double ans=0;

        for(int i=1;i<=n;++i){

            int cnt=0;

            for(int j=1;j<=n;++j){

                if(b[j][i]) ++cnt;

            }

            ans+=1.0/cnt;

        }

        printf("Case #%d: %.5lf\n",++ca,ans);

    }

    return 0;

}