bzoj1076 [SCOI2008]奖励关

#include<cstdio>
#include<iostream>
using namespace std;
double f[105][32770];
int need[20],w[20];
int K,n,x;
double ans;
int main()
{
scanf("%d%d",&K,&n);
for(int i=1;i<=n;i++)
{
scanf("%d%d",&w[i],&x);
while(x) need[i]|=1<<(x-1),scanf("%d",&x);
}
for(int i=K;i;i--)
for(int j=0;j<=1<<n;j++)
{
for(int k=1;k<=n;k++)
if((need[k]|j)==j) f[i][j]+=max(f[i+1][j],f[i+1][j|(1<<(k-1))]+w[k]);
else f[i][j]+=f[i+1][j];
f[i][j]/=1.*n;
}
printf("%.6lf",f[1][0]);
return 0;
}