#include <algorithm>
 
template< class ForwardIterator1, class ForwardIterator2 >
ForwardIterator2 swap_ranges( ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator1 first2 )

Exchanges elements between two given ranges: one defined by [first1, last1) and another starting at first2.

first1, last1 - the first range of the elements to be swapped

first2 - beginning of the second range of the elements to be swapped

iterator to the element past the last element exchanged in the range beginning with first2.

template<class ForwardIterator1, class ForwardIterator2>
ForwardIterator1 swap_ranges(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator1 first2)
{
    while (first1 != last1) {
        std::iter_swap(first1++, first2++);
    }
    return first2;
}

linear in the distance between first and last.

iter_swap, swap