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  1. #include <queue>
  2. #include <algorithm>
  3. #include <functional>
  4. #include <iostream>
  5. #include <string>
  6. #include <map>
  7.  
  8. struct SillyJob
  9. {
  10.     std::string description;
  11.     std::string priority;
  12.  
  13.     SillyJob(const std::string& d, const std::string& p)
  14.         : description(d), priority(p) { }
  15.  
  16.     bool operator<(const SillyJob& sj) const { return description.size() < sj.description.size(); }
  17.  
  18.     friend std::ostream& operator<<(std::ostream& os, const SillyJob& sj)
  19.     { return os << sj.priority << ": " << sj.description; }
  20. };
  21.  
  22. static bool by_priority(const SillyJob& a, const SillyJob& b)
  23. {
  24.     static std::map<std::string, int> prio_map;
  25.     if (prio_map.empty())
  26.     {
  27.         prio_map["HIGH"]   = 3;
  28.         prio_map["MEDIUM"] = 2;
  29.         prio_map["LOW"]    = 1;
  30.     }
  31.  
  32.     return prio_map[a.priority] < prio_map[b.priority];
  33. }
  34.  
  35. int main()
  36. {
  37.     std::cout << "Silly: (by description length)" << std::endl;
  38.     {
  39.         // by description length (member operator<)
  40.         std::priority_queue<SillyJob> silly_queue;
  41.  
  42.         silly_queue.push(SillyJob("short", "HIGH"));
  43.         silly_queue.push(SillyJob("very very long description", "LOW"));
  44.  
  45.         while (!silly_queue.empty())
  46.         {
  47.             std::cout << silly_queue.top() << std::endl;
  48.             silly_queue.pop();
  49.         }
  50.     }
  51.  
  52.     std::cout << std::string(60, '-') << "\nNot so silly: (by priority value)" << std::endl;
  53.     {
  54.         // by description length (member operator<)
  55.         typedef bool (*cmpf)(const SillyJob&, const SillyJob&);
  56.         typedef std::priority_queue<SillyJob, std::vector<SillyJob>, cmpf> not_so_silly_queue;
  57.  
  58.         not_so_silly_queue queue(by_priority);
  59.  
  60.         queue.push(SillyJob("short", "HIGH"));
  61.         queue.push(SillyJob("very very long description", "LOW"));
  62.  
  63.         while (!queue.empty())
  64.         {
  65.             std::cout << queue.top() << std::endl;
  66.             queue.pop();
  67.         }
  68.     }
  69.  
  70. }
  71.  
Success #stdin #stdout 0s 2872KB
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stdin
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Standard input is empty
stdout
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Silly: (by description length)
LOW: very very long description
HIGH: short
------------------------------------------------------------
Not so silly: (by priority value)
HIGH: short
LOW: very very long description
https://ideone.com/VEEQa
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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