bzoj 1076

最近好懒散QAQ

就是状压DP+概率。。由于顺着推还要计方案数略麻烦，所以就倒着推

#include<bits/stdc++.h>
#define inc(i,l,r) for(int i=l;i<=r;i++)
#define dec(i,l,r) for(int i=l;i>=r;i--)
#define link(x) for(edge *j=h[x];j;j=j->next)
#define mem(a) memset(a,0,sizeof(a))
#define inf 1e9
#define ll long long
#define succ(x) (1<<x)
#define NM 16
#define nm 100+5
using namespace std;
int read(){
    int x=0,f=1;char ch=getchar();
    while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
    while(isdigit(ch))x=x*10+ch-'0',ch=getchar();
    return x*f;
}
int n,m,a[NM],_t,d[succ(NM)];
double f[nm][succ(NM)];
int main(){
    freopen("data.in","r",stdin);
    n=read();m=read();
    inc(i,1,m){
        a[i]=read();
        while(_t=read())d[i]+=succ(_t-1);
    }
    _t=succ(m)-1;
    dec(i,n,1)
    inc(j,0,_t){
        inc(k,1,m)
        if((d[k]&j)==d[k])f[i][j]+=max(f[i+1][j|succ(k-1)]+a[k],f[i+1][j]);
        else f[i][j]+=f[i+1][j];
        f[i][j]/=m;
    }
//    inc(i,1,n){inc(j,0,_t)printf("%.1lf ",f[i][j]);printf("
");}
    printf("%.6lf",f[1][0]);
    return 0;
}