sort4

sort4.cpp

template <class _Compare, class _ForwardIterator>
unsigned __sort4(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3, _ForwardIterator __x4,
                 _Compare __c) {
  unsigned __r = _VSTD::__sort3<_Compare>(__x1, __x2, __x3, __c);
  if (__c(*__x4, *__x3)) {
    swap(*__x3, *__x4);
    ++__r;
    if (__c(*__x3, *__x2)) {
      swap(*__x2, *__x3);
      ++__r;
      if (__c(*__x2, *__x1)) {
        swap(*__x1, *__x2);
        ++__r;
      }
    }
  }
  return __r;
}