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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.  
  18. bool can(vector<pair<ll,ll>>& friends,ld mid)
  19. {
  20.     ld l = -1e15 , r = 1e15;
  21.     for (int i = 0; i < friends.size(); i++)
  22.     {
  23.         ld friend_pos = friends[i].first;
  24.         ld friend_speed = friends[i].second;
  25.         if(friend_pos >= l && friend_pos <= r)
  26.         {
  27.             l = max(l , friend_pos - friend_speed*mid);
  28.             r = min(r , friend_pos + friend_speed*mid);
  29.         }
  30.         else if(friend_pos < l)
  31.         {
  32.             if(friend_pos + friend_speed*mid >= l)
  33.             {
  34.                 r = min(r , friend_pos + friend_speed*mid);
  35.             }
  36.             else
  37.             {
  38.                 return false;
  39.             }
  40.         }
  41.         else if(friend_pos > r)
  42.         {
  43.             if(friend_pos - friend_speed*mid <= r)
  44.             {
  45.                 l = max(l , friend_pos - friend_speed*mid);
  46.             }
  47.             else
  48.             {
  49.                 return false;
  50.             }
  51.         }
  52.  
  53.     }
  54.     return true;
  55. }
  56.  
  57. int main()
  58. {
  59.     ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
  60.     int n; cin >> n;
  61.     //          pos|speed
  62.      vector<pair<ll,ll>> friends(n);
  63.     for (int i = 0; i < n; i++)
  64.     {
  65.         cin >> friends[i].first;
  66.     }    
  67.     for (int i = 0; i < n; i++)
  68.     {
  69.         cin >> friends[i].second;
  70.     }    
  71.     sort(all(friends));
  72.  
  73.     ld low = 0 , high = 1e15 , pos = -1;
  74.     for (int i = 0; i < 100; i++)
  75.     {
  76.         ld mid = (high+low)/2;
  77.         if(can(friends,mid))
  78.         {
  79.             pos = mid;
  80.             high = mid;
  81.         }
  82.         else
  83.         {
  84.             low = mid;
  85.         }
  86.     }
  87.     cout << fxd(10) << (ld)pos;
  88. }
Success #stdin #stdout 0.02s 5288KB
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Standard input is empty
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0.0000000000
https://ideone.com/V96UP4
language:
C++ (gcc 8.3)
created:
1 hour ago
visibility:
public

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