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  1.  
  2.  #include<bits/stdc++.h>
  3. using namespace std;
  4. #define pb push_back
  5. int n,m;
  6. double a[1005];
  7. double b[1005];
  8. double fun(double x) /// x is the initial fuel
  9. {
  10.     double prev=x;
  11.     double curr;
  12.     double used;
  13.     for(int i=0;i<n;i++)
  14.     {
  15.         used=1.0*(m+prev)/a[i];
  16.         prev=prev-used;
  17.         used=1.0*(m+prev)/b[i];
  18.         prev=prev-used;
  19.     }
  20.     if(prev<0)
  21.         return 0;
  22.     return 1;
  23.  
  24. }
  25. int main()
  26. {
  27.     cin>>n;
  28.     cin>>m;
  29.     for(int i=0;i<n;i++)
  30.     {
  31.         cin>>a[i];
  32.     }
  33.     for(int i=0;i<n;i++)
  34.     {
  35.         cin>>b[i];
  36.     }
  37.     double lo=0.0,hi=1000000000.000001,ans=-1,mid;
  38.     while(lo<=hi)
  39.     {
  40.         mid=1.0*(lo+hi)/2;
  41.         if(fun(mid))
  42.         {
  43.             ans=mid;
  44.             hi=mid-0.000001;
  45.         }
  46.         else
  47.         {
  48.             lo=mid+0.000001;
  49.         }
  50.     }
  51.     if(ans<0)
  52.     {
  53.         cout<<-1<<endl;
  54.         return 0;
  55.     }
  56.     cout<<fixed<<setprecision(6)<<ans<<endl;
  57. }
Success #stdin #stdout 0s 4536KB
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stdin
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Standard input is empty
stdout
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0.000001
https://ideone.com/lH4hwr
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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