[BZOJ 1076][SCOI2008]奖励关：状压DP

/*
User:Small
Language:C++
Problem No.:1076
*/
#include<bits/stdc++.h>
#define ll long long
#define inf 999999999
using namespace std;
const int M=(1<<15)+5;
int k,n,d[16],p[16],v[16];
double f[101][M];
int main(){
freopen("data.in","r",stdin);//
p[1]=1;
for(int i=2;i<=16;i++) p[i]=p[i-1]<<1;
scanf("%d%d",&k,&n);
for(int i=1;i<=n;i++){
scanf("%d",&v[i]);
int x;
while(scanf("%d",&x)==1&&x) d[i]|=p[x];
}
for(int i=k;i;i--){
for(int j=0;j<p[n+1];j++){
for(int t=1;t<=n;t++){
if((d[t]&j)==d[t]) f[i][j]+=max(f[i+1][j],f[i+1][j|p[t]]+v[t]);
else f[i][j]+=f[i+1][j];
}
f[i][j]/=n;
}
}
printf("%.6lf",f[1][0]);
return 0;
}