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离散型概率

状压DP

#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <sstream>
#include <iostream>
#include <cstdlib>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <vector>
#include <algorithm>
#include <functional>
using namespace std;
#define ll long long
#define re register
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define P pair<int,int>
void read(int &a)
{
    a=0;
    int d=1;
    char ch;
    while(ch=getchar(),!isdigit(ch))
        if(ch=='-')
            d=-1;
    a=ch^48;
    while(ch=getchar(),isdigit(ch))
        a=(a<<3)+(a<<1)+(ch^48);
    a*=d;
}
void write(int x)
{
    if(x<0)
        putchar(45),x=-x;
    if(x>9)
        write(x/10);
    putchar(x%10+'0');
}
double f[105][1<<15];
int sta[20],a[20];
int main()
{
    int k,n;
    read(k);
    read(n);
    for(re int i=1;i<=n;i++)
    {
        read(a[i]);
        int x;
        read(x);
        if(!x)
            continue;
        sta[i]|=(1<<x-1);
        while(x)
        {
            read(x);
            if(!x)
                break;
            sta[i]|=(1<<x-1);
        }
    }
    for(re int i=1;i<=k;i++)
    {
        for(re int j=0;j<(1<<n);j++)///枚举状态
        {
            for(re int l=1;l<=n;l++)///枚举物品
                if((j&sta[l])==sta[l])///判断该状态能否转移
                    f[i][j]+=max(f[i-1][j],f[i-1][j|(1<<l-1)]+a[l]);
                else
                    f[i][j]+=f[i-1][j];
            f[i][j]/=n;///乘上该事件发生的概率
        }
    }
    printf("%.6lf",f[k][0]);
    return 0;
}