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  1. #include <bits/stdc++.h>
  2. #include <ext/pb_ds/assoc_container.hpp>
  3. #include <ext/pb_ds/tree_policy.hpp>
  4.  
  5. using namespace std;
  6. using namespace __gnu_pbds;
  7. using ll = long long;
  8. using ld = long double;
  9.  
  10. #define all(x)  x.begin(),x.end()
  11. #define v(x) vector<x>
  12. #define nl '\n'
  13. #define fxd(x) fixed << setprecision(x)
  14. template<class t> using ordered_set = tree<t, null_type, less<t>, rb_tree_tag, tree_order_statistics_node_update>;
  15. template<class t> using ordered_multiset = tree<t, null_type, less_equal<t>, rb_tree_tag, tree_order_statistics_node_update>;
  16.  
  17. vector<pair<ll,ll>> pr; 
  18. ll n , k ; 
  19.  
  20. bool can(double x)
  21. {
  22.     sort(all(pr),[&](pair<ll,ll> fr , pair<ll,ll> sc){
  23.         return ((double)fr.first - x * (double)fr.second) > ((double)sc.first - x * (double)sc.second);
  24.     });
  25.     double sum = 0;
  26.     for (int i = 0; i < k; i++)
  27.     {
  28.         sum+= (double)pr[i].first - x*(double)pr[i].second;
  29.     }
  30.     return sum >= 0;
  31. }
  32. int main()
  33. {
  34.     ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
  35.     cin >> n >> k;
  36.     pr.resize(n);
  37.     for (int i = 0; i < n; i++)
  38.     {
  39.         cin >> pr[i].first;
  40.         cin >> pr[i].second;
  41.     }
  42.  
  43.     double l = 0,r = 1e10,pos = -1,mid;
  44.  
  45.     for (int i = 0; i < 70; i++)
  46.     {
  47.         mid = (l + r)/2;
  48.         if(can(mid))
  49.         {
  50.             pos = mid;
  51.             l = mid;
  52.         }
  53.         else
  54.         {
  55.             r = mid;
  56.         }
  57.     }
  58.  
  59.     cout << fxd(10) <<pos;
  60.  
  61. }
Success #stdin #stdout 0s 5304KB
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stdin
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Standard input is empty
stdout
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10000000000.0000000000
https://ideone.com/ndjJP9
language:
C++14 (gcc 8.3)
created:
11 hours ago
visibility:
public

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