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  1. #include <utility>
  2. #include <cstddef>
  3. #include <vector>
  4.  
  5. using std::size_t;
  6.  
  7. namespace details {
  8. template<typename Lambda>
  9.     void for_each_multiset_combo_worker( std::vector<size_t> const& counts, Lambda&& lambda, size_t depth, std::vector<size_t>& current )
  10.     {
  11.         if (depth >= counts.size()) {
  12.             lambda( current );
  13.             return;
  14.         }
  15.         for (size_t i = 0; i <= counts[depth]; ++i) {
  16.             current.push_back(i);
  17.             for_each_multiset_combo_worker( counts, lambda, depth+1, current );
  18.             current.pop_back();
  19.         }
  20.     }
  21. }
  22. template<typename Lambda>
  23. void for_each_multiset_combo( std::vector<size_t> const& counts, Lambda&& lambda )
  24. {
  25.     std::vector<size_t> current;
  26.     current.reserve( counts.size() );
  27.     details::for_each_multiset_combo_worker( counts, std::forward<Lambda>(lambda), 0, current );
  28. }
  29. #include <iostream>
  30.  
  31. int main() {
  32.     std::vector<size_t> multiset = {3, 2, 1, 1};
  33.     size_t counter = 0;
  34.     for_each_multiset_combo( multiset, [&]( std::vector<size_t> const& counts ){
  35.         std::cout << counter << ": [";
  36.         for(auto it = counts.begin(); it != counts.end(); ++it) {
  37.             if (it != counts.begin()) {
  38.                 std::cout << ", ";
  39.             }
  40.             std::cout << *it;
  41.         }
  42.         std::cout << "]\n";
  43.         ++counter;
  44.     });
  45. }
Success #stdin #stdout 0s 2988KB
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stdin
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Standard input is empty
stdout
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0: [0, 0, 0, 0]
1: [0, 0, 0, 1]
2: [0, 0, 1, 0]
3: [0, 0, 1, 1]
4: [0, 1, 0, 0]
5: [0, 1, 0, 1]
6: [0, 1, 1, 0]
7: [0, 1, 1, 1]
8: [0, 2, 0, 0]
9: [0, 2, 0, 1]
10: [0, 2, 1, 0]
11: [0, 2, 1, 1]
12: [1, 0, 0, 0]
13: [1, 0, 0, 1]
14: [1, 0, 1, 0]
15: [1, 0, 1, 1]
16: [1, 1, 0, 0]
17: [1, 1, 0, 1]
18: [1, 1, 1, 0]
19: [1, 1, 1, 1]
20: [1, 2, 0, 0]
21: [1, 2, 0, 1]
22: [1, 2, 1, 0]
23: [1, 2, 1, 1]
24: [2, 0, 0, 0]
25: [2, 0, 0, 1]
26: [2, 0, 1, 0]
27: [2, 0, 1, 1]
28: [2, 1, 0, 0]
29: [2, 1, 0, 1]
30: [2, 1, 1, 0]
31: [2, 1, 1, 1]
32: [2, 2, 0, 0]
33: [2, 2, 0, 1]
34: [2, 2, 1, 0]
35: [2, 2, 1, 1]
36: [3, 0, 0, 0]
37: [3, 0, 0, 1]
38: [3, 0, 1, 0]
39: [3, 0, 1, 1]
40: [3, 1, 0, 0]
41: [3, 1, 0, 1]
42: [3, 1, 1, 0]
43: [3, 1, 1, 1]
44: [3, 2, 0, 0]
45: [3, 2, 0, 1]
46: [3, 2, 1, 0]
47: [3, 2, 1, 1]
https://ideone.com/8GN1xx
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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