The function partial_sort_copy is used to copy a partially sorted sequence.
template<class InputIterator, class RandomAccessIterator> RandomAccessIterator partial_sort_copy (InputIterator first, InputIterator last, RandomAccessIterator result_first, RandomAccessIterator result_last); template<class InputIterator, class RandomAccessIterator, class Compare> RandomAccessIterator partial_sort_copy (InputIterator first, InputIterator last, RandomAccessIterator result_first, RandomAccessIterator result_last,Compare comp);
The position at the end of the copied elements is returned.