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;

}

template<class Iterator>

bool next_permutation(Iterator first, Iterator mid, Iterator last)

{

std::reverse(mid, last);

return std::next_permutation(first, last);

}