combinations.hxx
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5  * Copyright (c) Michael Jeulin-Lagarrigue
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20 #ifndef MODULE_COMBINATORY_COMBINATIONS_HXX
21 #define MODULE_COMBINATORY_COMBINATIONS_HXX
22 
23 // STD includes
24 #include <list>
25 
26 namespace huc
27 {
28  namespace combinatory
29  {
44  template <typename Container, typename IT>
45  std::list<Container> Combinations(const IT& begin, const IT& end)
46  {
47  std::list<Container> combinations;
48 
49  // Recusion termination
50  const auto kSeqSize = static_cast<const int>(std::distance(begin, end));
51  if (kSeqSize <= 0)
52  return combinations;
53 
54  // Keep first element
55  Container elementContainer;
56  elementContainer.push_back(*begin);
57  combinations.push_back(elementContainer);
58 
59  // Recursion termination
60  if (kSeqSize == 1)
61  return combinations;
62 
63  // Build all permutations of the suffix - Recursion
64  auto subCombinations = Combinations<Container, IT>(begin + 1, end);
65 
66  // Put the letter into every possible position of the existing permutations.
67  for (auto it = subCombinations.begin(); it != subCombinations.end(); ++it)
68  {
69  combinations.push_back(*it);
70  it->push_back(*begin);
71  combinations.push_back(*it);
72  }
73 
74  return combinations;
75  }
76  }
77 }
78 
79 #endif // MODULE_COMBINATORY_COMBINATIONS_HXX
std::list< Container > Combinations(const IT &begin, const IT &end)