fork(1) download
copy 
  1. #include <tuple>
  2. #include <unordered_map>
  3. #include <cassert>
  4. #include <iostream>
  5.  
  6. struct triplet 
  7. { 
  8. 	unsigned a,b,c;
  9. 	bool operator< (triplet const& o) const { return std::tie(a,b,c) < std::tie(o.a,o.b,o.c); }
  10. 	bool operator==(triplet const& o) const { return std::tie(a,b,c) ==std::tie(o.a,o.b,o.c); }
  11. };
  12.  
  13. namespace std {
  14.     template<> struct hash<triplet> {
  15.         unsigned int operator()(triplet const& key) const { 
  16.             return  ~key.a + 17u*key.b + 17u*key.c; // totally made that up, could be better, I suppose
  17.         }
  18.     };
  19. }
  20.  
  21. static std::ostream& operator<<(std::ostream& os, triplet const& key) {
  22.     return os << '[' << key.a << ',' << key.b << ',' << key.c << ']';
  23. }
  24.  
  25. int main()
  26. {
  27.     std::unordered_multimap<triplet, double> map;
  28.  
  29.     // insert items dynamically
  30.     map.insert({ triplet{ /*I*/ 1, /*J*/ 2, /*K*/ 3 },  0.1 } );
  31.     map.insert({ triplet{ /*I*/ 4, /*J*/ 5, /*K*/ 6 },  0.2 } );
  32.     map.insert({ triplet{ /*I*/ 7, /*J*/ 8, /*K*/ 9 },  0.3 } );
  33.     map.insert({ triplet{ /*I*/ 1, /*J*/ 2, /*K*/ 0 },  0.4 } ); // duplicate (I,J) ok
  34.  
  35.     map.insert({ triplet{ /*I*/ 1, /*J*/ 2, /*K*/ 0 }, 0.5 } );
  36.  
  37.     assert(0 == map.count(triplet {1,5,6}));
  38.     assert(1 == map.count(triplet {4,5,6}));
  39.  
  40.     auto range = map.equal_range(triplet { 1,2,0 });
  41.     for (auto it=range.first; it!=range.second; ++it)
  42.         std::cout << it->first << ": " << it->second << "\n";
  43. }
  44.  
Success #stdin #stdout 0s 3020KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
[1,2,0]: 0.4
[1,2,0]: 0.5
https://ideone.com/pm8Oz
language:
C++14 (gcc 8.3)
created:
13 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!