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  1. #include <iostream>
  2. #include <vector>
  3. #include <functional>
  4.  
  5. using namespace std;
  6.  
  7. bool nextSubsetIndex(std::vector<int> &a, int n) {
  8.     for (int i = a.size() - 1; i >=0; --i) {
  9.         n--;
  10.         if (a[i] < n) {
  11.             int x = ++a[i];
  12.             for (int j = i + 1; j < a.size(); ++j) {
  13.                 a[j] = ++x;
  14.             }
  15.             return true;
  16.         }
  17.     }
  18.  
  19.     return false;
  20. }
  21.  
  22. void generateSubset(int n, int k, std::function<void(const std::vector<int> &)> f) {
  23.     std::vector<int> a(k);
  24.  
  25.     for (size_t i=0; i<k; ++i) {
  26.         a[i] = i;
  27.     }
  28.  
  29.     do {
  30.           f(a);
  31.     } while (nextSubsetIndex(a, n));
  32. }
  33.  
  34. int main() {
  35. 	int n, k;
  36.  
  37.     while (std::cin >> n >> k) {
  38.        generateSubset(n, k, [](auto a) {
  39.            for (auto x : a) {
  40.               std::cout << x  + 1 << ", ";
  41.            }
  42.            std::cout << '\n';
  43.        });
  44.        std::cout << "------\n";
  45.     }
  46.  
  47. 	return 0;
  48. }
Success #stdin #stdout 0s 4460KB
comments (?)
stdin
copy 
5 2
5 3
stdout
copy 
1, 2, 
1, 3, 
1, 4, 
1, 5, 
2, 3, 
2, 4, 
2, 5, 
3, 4, 
3, 5, 
4, 5, 
------
1, 2, 3, 
1, 2, 4, 
1, 2, 5, 
1, 3, 4, 
1, 3, 5, 
1, 4, 5, 
2, 3, 4, 
2, 3, 5, 
2, 4, 5, 
3, 4, 5, 
------
https://ideone.com/EyVBbQ
Subset
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
secret

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