next_permutation用于powerset中的组合或子集 [英] next_permutation for combinations or subsets in powerset

问题描述

有没有一些等效的库或函数，给我下一个值的组合，如next_permutation对我来说？

Is there some equivalent library or function that will give me the next combination of a set of values like next_permutation in does for me?

推荐答案

组合：从Mark Nelson的同一主题的文章，我们有next_combination http://marknelson.us/2002 / 03/01 / next-permutation

排列：从STL我们有std :: next_permutation

Combinations: from Mark Nelson's article on the same topic we have next_combination http://marknelson.us/2002/03/01/next-permutation
Permutations: from STL we have std::next_permutation

 template <typename Iterator>
 inline bool next_combination(const Iterator first, Iterator k, const Iterator last)
 {
    if ((first == last) || (first == k) || (last == k))
       return false;
    Iterator itr1 = first;
    Iterator itr2 = last;
    ++itr1;
    if (last == itr1)
       return false;
    itr1 = last;
    --itr1;
    itr1 = k;
    --itr2;
    while (first != itr1)
    {
       if (*--itr1 < *itr2)
       {
          Iterator j = k;
          while (!(*itr1 < *j)) ++j;
          std::iter_swap(itr1,j);
          ++itr1;
          ++j;
          itr2 = k;
          std::rotate(itr1,j,last);
          while (last != j)
          {
             ++j;
             ++itr2;
          }
          std::rotate(k,itr2,last);
          return true;
       }
    }
    std::rotate(first,k,last);
    return false;
 }

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