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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. template <class T>
  5. struct PQ {
  6.   vector<T> v;
  7.   function<bool(const T&, const T&)> comp;
  8.  
  9.   PQ() : comp(less<T>()) {}
  10.  
  11.   void push(const T& value) {
  12.     v.push_back(value);
  13.     push_heap(v.begin(), v.end(), comp);
  14.   }
  15.  
  16.   void pop() {
  17.     pop_heap(v.begin(), v.end(), comp);
  18.     v.pop_back();
  19.   }
  20.  
  21.   const T& top() {
  22.     return v.front();
  23.   }
  24.  
  25.   bool empty() {
  26.     return v.empty();
  27.   }
  28.  
  29.   void change_comparator(function<bool(const T&, const T&)> other_comp) {
  30.     comp = other_comp;
  31.     make_heap(v.begin(), v.end(), comp);
  32.   }
  33. };
  34.  
  35. template <class T>
  36. void print(PQ<T> pq) {
  37.   while (!pq.empty()) {
  38.     cout << pq.top() << " ";
  39.     pq.pop();
  40.   }
  41.   cout << "\n";
  42. }
  43.  
  44. int main() {
  45.   ios::sync_with_stdio(false);
  46.   cin.tie(0);
  47.   PQ<int> pq;
  48.   for (int i = 1; i <= 10; ++i) {
  49.     pq.push(i);
  50.   }
  51.   print(pq);
  52.   pq.change_comparator(greater<int>());
  53.   print(pq);
  54.   return 0;
  55. }
  56.  
Success #stdin #stdout 0s 5524KB
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Standard input is empty
stdout
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10 9 8 7 6 5 4 3 2 1 
1 2 3 4 5 6 7 8 9 10
https://ideone.com/jBJc9w
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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