新人求助，奖励关那题，不开O2 AC 开O2 WA

#include<bits/stdc++.h>
using namespace std;

#define MAXN 15
#define MK 105
#define db long double

inline db max(db a,db b)
{
	if(a > b) return a;
	else return b;
}

db f[MK][1<<15];
int n,m;
int s[MAXN][MAXN],a[MAXN],p[MAXN]; 

void rd()
{
	scanf("%d%d",&m,&n);
	for(int i = 1; i <= n; i ++) {
		scanf("%d",&a[i]);
		for(int j = 1; j <= n; j ++)
		{
			scanf("%d",&s[i][j]);
			if(s[i][j] == 0) break;
			p[i] |= (1<<(s[i][j]-1));
		}
	}	
}

signed main()
{
	rd();
	for(int i = m; i >= 1; i --)
		for(int j = 0; j < (1<<n); j ++) {
			for(register int k = 1; k <= n; k ++)
			{
				if((p[k] & j) == p[k])
				{
					f[i][j] += max(f[i+1][j],f[i+1][j|(1<<(k-1))] + a[k]);
				} else f[i][j] += f[i+1][j];
			}
			f[i][j] /= n;
		}
	printf("%.6Lf",f[1][0]);
	return 0;
 }