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  1. #include <array>
  2. #include <bitset>
  3. #include <iostream>
  4.  
  5. template <std::size_t N>
  6. bool increase(std::bitset<N>& bs)
  7. {
  8.     for (std::size_t i = 0; i != bs.size(); ++i) {
  9.         if (bs.flip(i).test(i) == true) {
  10.             return true;
  11.         }
  12.     }
  13.     return false; // overflow
  14. }
  15.  
  16. template <typename T, std::size_t N>
  17. void display(const std::array<T, N>& a, const std::bitset<N>& bs)
  18. {
  19.     std::cout << '{';
  20.     const char* sep = "";
  21.  
  22.     for (std::size_t i = 0; i != bs.size(); ++i) {
  23.         if (bs.test(i)) {
  24.             std::cout << sep << a[i];
  25.             sep = ", ";
  26.         }
  27.     }
  28.     std::cout << '}' << std::endl;
  29. }
  30.  
  31. template <typename T, std::size_t N>
  32. void display_all_subsets(const std::array<T, N>& a)
  33. {
  34.     std::bitset<N> bs;
  35.  
  36.     do {
  37.         display(a, bs);
  38.     } while (increase(bs));
  39. }
  40.  
  41. int main()
  42. {
  43.     const std::array<int, 3> a = {1, 2, 3};
  44.     display_all_subsets(a);
  45.  
  46.     return 0;
  47. }
Success #stdin #stdout 0s 3340KB
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Standard input is empty
stdout
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{}
{1}
{2}
{1, 2}
{3}
{1, 3}
{2, 3}
{1, 2, 3}
https://ideone.com/GfjPe7
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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