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  1. #include <algorithm>
  2. #include <functional>
  3. #include <iostream>
  4. #include <vector>
  5.  
  6. void permutationUtilInner(std::vector<int> v, std::function<void (const std::vector<int>&)> f)
  7. {
  8.     do {
  9.         f(v);
  10.     } while (std::next_permutation(v.begin(), v.end()));
  11. }
  12.  
  13. void permutationUtil(std::vector<int> v, std::size_t r, std::function<void (const std::vector<int>&)> f)
  14. {
  15.     std::vector<bool> b(v.size() - r, false);
  16.     b.resize(v.size(), true);
  17.  
  18.     std::sort(v.begin(), v.end());
  19.     do {
  20.         std::vector<int> sub;
  21.  
  22.         for (std::size_t i = 0; i != b.size(); ++i) {
  23.             if (b[i]) {
  24.                 sub.push_back(v[i]);
  25.             }
  26.         }
  27.         permutationUtilInner(sub, f);
  28.     } while (std::next_permutation(b.begin(), b.end()));
  29. }
  30.  
  31. void print_vector(const std::vector<int>& v)
  32. {
  33.     const char* sep = "";
  34.     std::cout << '{';
  35.     for (const auto e : v) {
  36.         std::cout << sep << e;
  37.         sep = ", ";
  38.     }
  39.     std::cout << "}\n";
  40. }
  41.  
  42.  
  43. int main()
  44. {
  45.     permutationUtil({1, 2, 3, 4}, 3, &print_vector);
  46. }
Success #stdin #stdout 0s 3420KB
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stdin
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Standard input is empty
stdout
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{2, 3, 4}
{2, 4, 3}
{3, 2, 4}
{3, 4, 2}
{4, 2, 3}
{4, 3, 2}
{1, 3, 4}
{1, 4, 3}
{3, 1, 4}
{3, 4, 1}
{4, 1, 3}
{4, 3, 1}
{1, 2, 4}
{1, 4, 2}
{2, 1, 4}
{2, 4, 1}
{4, 1, 2}
{4, 2, 1}
{1, 2, 3}
{1, 3, 2}
{2, 1, 3}
{2, 3, 1}
{3, 1, 2}
{3, 2, 1}
https://ideone.com/17ZsnY
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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