uva 10883

#include<cstring>#include<cstdio>#include<cmath>#include<algorithm>using namespace std;int main(){int T,t=1,n;scanf("%d",&T);while(T--){scanf("%d",&n);double res=0,c1=0,t1=(n-1)*log(2);    for(int i=0;i<n;i++)    {    double a;    scanf("%lf",&a);    if(i>0)    c1+=log(n-i)-log(i);    if(a>0)    res+=exp(log(a)+c1-t1);    else    res-=exp(log(-a)+c1-t1);}printf("Case #%d: %.3f\n",t++,res);}}