題目連結：https://vjudge.net/problem/ZOJ-3329

#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<iostream>
#include<set>
#include<map>
#include<cmath>
#include<sstream>
#include<vector>
#include<stack>
#include<queue>
#include<algorithm>
#define fin freopen("a.txt","r",stdin)
#define fout freopen("a.txt","w",stdout)
typedef long long LL;
using namespace std;
typedef pair<int, int> P;
const int INF = 1e8 + 10;
const int maxn = 1000 + 10;
double A[maxn], B[maxn], p[maxn], p0;
int n, k1, k2, k3, a, b, c;

int main()
{
	//fin;
	int T;
	scanf("%d", &T);
	while(T--)
	{
		cin >> n >> k1 >> k2 >> k3 >> a >> b >> c;
        p0 = 1.0/(k1*k2*k3);
        memset(p, 0, sizeof p);
        memset(A, 0, sizeof A);
        memset(B, 0, sizeof B);
        for(int i = 1; i <= k1; i++)
          for(int j = 1; j <= k2; j++)
          	for(int k = 1; k <= k3; k++)
          		if(i != a || j != b || k != c)
          		   p[i+j+k] += p0;
        for(int i = n; i >= 0; i--)
        {
        	A[i] = p0; B[i] = 1.0;
        	for(int k = 3; k + i <= n; k++)
        	{
        		A[i] += p[k]*A[i+k];
        		B[i] += p[k]*B[i+k];
        	}
        }
        printf("%.12f\n", B[0]/(1.0-A[0]));
	}
	return 0;
}