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  1. #include <iostream>
  2. #include <bits/stdc++.h>
  3.  
  4.  
  5. using namespace std;
  6. #define ll long long
  7. ll x,y,p,q;
  8. ll f(ll a)
  9. {
  10.  
  11.     ll num=(a*p-x);
  12.     ll denum=(a*q-y);
  13.     if(denum<0||num<0)
  14.     {
  15.         return 0;
  16.     }
  17.     if(denum>=num)
  18.     {
  19.         return 1;
  20.     }
  21.     else
  22.     {
  23.         return 0;
  24.     }
  25. }
  26. int main()
  27. {
  28.     //cout << "Hello world!" << endl;
  29.     ll i,j ,k,t;
  30.     cin>>t;
  31.     while(t--)
  32.     {
  33.         cin>>x>>y>>p>>q;
  34.  
  35.         if((double)x/y==(double)p/q)
  36.         {
  37.             cout<<"0\n";
  38.             continue;
  39.         }
  40.         if(p>=q&&x!=y)
  41.         {
  42.             cout<<"-1\n";
  43.             continue;
  44.         }
  45.         ll lo=(x/p),hi=10e9;
  46.     ll mid;
  47.     ll last=-1;
  48.     while(lo<hi)
  49.     {
  50.  
  51.         mid=lo+(hi-lo)/2;
  52.  
  53.         if(f(mid))
  54.         {
  55.             last=mid;
  56.             hi=mid;
  57.         }
  58.         else
  59.         {
  60.             lo=mid+1;
  61.         }
  62.     }
  63.     ll  ans=(q*last-y);
  64.     cout<<ans<<"\n";
  65.     }
  66.  
  67.     return 0;
  68. }
  69.  
Runtime error #stdin #stdout 0s 15240KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
https://ideone.com/GkH1J6
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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