Electroneum
combinator.h
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29 // Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
30 
31 #pragma once
32 
33 #include <iostream>
34 #include <vector>
35 #include <stdexcept>
36 #include <cstdint>
37 
38 namespace tools {
39 
41 
42 template<typename T>
43 class Combinator {
44 public:
45  Combinator(const std::vector<T>& v) : origin(v) { }
46 
47  std::vector<std::vector<T>> combine(size_t k);
48 
49 private:
50  void doCombine(size_t from, size_t k);
51 
52  std::vector<T> origin;
53  std::vector<std::vector<T>> combinations;
54  std::vector<size_t> current;
55 };
56 
57 template<typename T>
58 std::vector<std::vector<T>> Combinator<T>::combine(size_t k)
59 {
60  if (k > origin.size())
61  {
62  throw std::runtime_error("k must be smaller than elements number");
63  }
64 
65  if (k == 0)
66  {
67  throw std::runtime_error("k must be greater than zero");
68  }
69 
70  combinations.clear();
71  doCombine(0, k);
72  return combinations;
73 }
74 
75 template<typename T>
76 void Combinator<T>::doCombine(size_t from, size_t k)
77 {
78  current.push_back(0);
79 
80  for (size_t i = from; i <= origin.size() - k; ++i)
81  {
82  current.back() = i;
83 
84  if (k > 1) {
85  doCombine(i + 1, k - 1);
86  } else {
87  std::vector<T> comb;
88  for (auto ind: current) {
89  comb.push_back(origin[ind]);
90  }
91  combinations.push_back(comb);
92  }
93  }
94 
95  current.pop_back();
96 }
97 
98 } //namespace tools
Combinator(const std::vector< T > &v)
Definition: combinator.h:45
uint64_t combinations_count(uint32_t k, uint32_t n)
Definition: combinator.cpp:35
unsigned int uint32_t
Definition: stdint.h:126
Various Tools.
Definition: tools.cpp:31
unsigned __int64 uint64_t
Definition: stdint.h:136
std::vector< std::vector< T > > combine(size_t k)
Definition: combinator.h:58