COOKIE-CLICKER-ALPHA

#include<iostream>
#include<stdio.h>
#include<vector>
#include<algorithm>
double gen_cookie_time(double c,double f,double x)
{
  if(x<=2)
    return x/2.;
  double f1=2,buy_time=0;
  std::vector<double> v;
  v.push_back(x/f1);
  while(f1<=1e+7)
  {
    buy_time+=c/f1;
    f1+=f;
    double wait_time=buy_time+x/f1;
    v.push_back(wait_time);
  }
  return *std::min_element(v.begin(),v.end());
}
int main()
{
  int t;
  std::cin>>t;
  for(int i=1;i<=t;++i)
  {
    double c,f,x;
    std::cin>>c>>f>>x;
    double time=gen_cookie_time(c,f,x);
    printf("Case #%d: %.7lf\n",i,time);
  }
  return 0;
}