mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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208 lines
7.6 KiB
C++
208 lines
7.6 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2019 Bolero MURAKAMI
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https://github.com/bolero-MURAKAMI/Sprout
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef SPROUT_ALGORITHM_MINMAX_ELEMENT_HPP
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#define SPROUT_ALGORITHM_MINMAX_ELEMENT_HPP
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#include <iterator>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/iterator/operation.hpp>
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#include <sprout/iterator/type_traits/category.hpp>
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#include <sprout/utility/pair/pair.hpp>
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#include <sprout/utility/pair/access.hpp>
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#include HDR_FUNCTIONAL_SSCRISK_CEL_OR_SPROUT
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namespace sprout {
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namespace detail {
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template<typename ForwardIteratorPair, typename Compare>
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inline SPROUT_CONSTEXPR ForwardIteratorPair
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iter_minmax_pair(ForwardIteratorPair const& a, ForwardIteratorPair const& b, Compare comp) {
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return ForwardIteratorPair(
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comp(*sprout::first(b), *sprout::first(a)) ? sprout::first(b) : sprout::first(a),
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comp(*sprout::second(b), *sprout::second(a)) ? sprout::second(a) : sprout::second(b)
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);
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}
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template<typename ForwardIteratorPair, typename ForwardIterator, typename Compare>
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inline SPROUT_CONSTEXPR ForwardIteratorPair
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iter_minmax(ForwardIteratorPair const& a, ForwardIterator const& b, Compare comp) {
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return ForwardIteratorPair(
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comp(*b, *sprout::first(a)) ? b : sprout::first(a),
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comp(*b, *sprout::second(a)) ? sprout::second(a) : b
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);
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}
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template<typename ForwardIterator, typename Compare>
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inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, ForwardIterator>
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iter_minmax(ForwardIterator const& a, ForwardIterator const& b, Compare comp) {
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typedef sprout::pair<ForwardIterator, ForwardIterator> type;
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return comp(*b, *a)
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? type(b, a)
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: type(a, b)
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;
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}
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template<typename RandomAccessIterator, typename Compare>
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inline SPROUT_CONSTEXPR sprout::pair<RandomAccessIterator, RandomAccessIterator>
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minmax_element_impl_ra(
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RandomAccessIterator const& first, Compare comp,
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typename std::iterator_traits<RandomAccessIterator>::difference_type half
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)
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{
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return half == 1
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? iter_minmax(first, sprout::next(first), comp)
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: sprout::detail::iter_minmax_pair(
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sprout::detail::minmax_element_impl_ra(
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first, comp, half / 2
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),
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sprout::detail::minmax_element_impl_ra(
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sprout::next(first, half - (half & 1)), comp, (half + 1) / 2
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),
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comp
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)
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;
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}
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template<typename RandomAccessIterator, typename Compare>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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sprout::is_constant_distance_iterator<RandomAccessIterator>::value,
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sprout::pair<RandomAccessIterator, RandomAccessIterator>
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>::type
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minmax_element(
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RandomAccessIterator const& first, RandomAccessIterator const& last, Compare comp,
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std::random_access_iterator_tag*
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)
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{
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return first == last || sprout::next(first) == last
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? sprout::pair<RandomAccessIterator, RandomAccessIterator>(first, first)
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: sprout::distance(first, last) % 2 == 0
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? sprout::detail::minmax_element_impl_ra(
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first, comp,
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sprout::distance(first, last) / 2
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)
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: sprout::detail::iter_minmax(
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sprout::detail::minmax_element_impl_ra(
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first, comp,
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sprout::distance(first, last) / 2
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),
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sprout::prev(last),
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comp
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)
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;
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}
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template<typename ForwardIterator, typename Compare>
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inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> >
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minmax_element_impl_3(
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sprout::pair<ForwardIterator, ForwardIterator> minmax,
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ForwardIterator const& first, ForwardIterator const& next,
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ForwardIterator const& last, Compare comp) {
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typedef sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> > type;
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return next == last
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? type(
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next,
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sprout::detail::iter_minmax(minmax, first, comp)
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)
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: type(
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sprout::next(next),
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sprout::detail::iter_minmax_pair(
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minmax,
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sprout::detail::iter_minmax(first, next, comp),
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comp
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)
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)
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;
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}
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template<typename ForwardIterator, typename Compare>
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inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> >
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minmax_element_impl_1(
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sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> > const& current,
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ForwardIterator const& last, Compare comp, typename std::iterator_traits<ForwardIterator>::difference_type n
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)
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{
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return current.first == last ? current
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: n == 1 ? sprout::detail::minmax_element_impl_3(
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current.second, current.first, sprout::next(current.first),
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last, comp)
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: sprout::detail::minmax_element_impl_1(
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sprout::detail::minmax_element_impl_1(
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current,
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last, comp, n / 2
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),
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last, comp, n - n / 2
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)
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;
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}
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template<typename ForwardIterator, typename Compare>
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inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> >
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minmax_element_impl(
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sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> > const& current,
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ForwardIterator const& last, Compare comp, typename std::iterator_traits<ForwardIterator>::difference_type n
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)
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{
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return current.first == last ? current
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: sprout::detail::minmax_element_impl(
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sprout::detail::minmax_element_impl_1(
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current,
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last, comp, n
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),
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last, comp, n * 2
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)
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;
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}
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template<typename ForwardIterator, typename Compare>
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inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> >
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minmax_element_impl_2(
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ForwardIterator const& first, ForwardIterator const& next, ForwardIterator const& last, Compare comp
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)
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{
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typedef sprout::pair<ForwardIterator, ForwardIterator> type;
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return next == last ? sprout::pair<ForwardIterator, type>(next, type(first, first))
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: sprout::pair<ForwardIterator, type>(sprout::next(next), iter_minmax(first, next, comp))
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;
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}
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template<typename ForwardIterator, typename Compare>
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inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, ForwardIterator>
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minmax_element(
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ForwardIterator const& first, ForwardIterator const& last, Compare comp,
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std::forward_iterator_tag*
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)
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{
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return first == last ? sprout::pair<ForwardIterator, ForwardIterator>(first, first)
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: sprout::detail::minmax_element_impl(
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sprout::detail::minmax_element_impl_2(first, sprout::next(first), last, comp),
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last, comp, 1).second
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;
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}
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} // namespace detail
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// 25.4.7 Minimum and maximum
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//
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// recursion depth:
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// O(log N)
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//
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template<typename ForwardIterator, typename Compare>
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inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, ForwardIterator>
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minmax_element(ForwardIterator first, ForwardIterator last, Compare comp) {
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typedef typename std::iterator_traits<ForwardIterator>::iterator_category* category;
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return sprout::detail::minmax_element(first, last, comp, category());
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}
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template<typename ForwardIterator>
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inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, ForwardIterator>
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minmax_element(ForwardIterator first, ForwardIterator last) {
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return sprout::minmax_element(
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first, last,
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NS_SSCRISK_CEL_OR_SPROUT::less<typename std::iterator_traits<ForwardIterator>::value_type>()
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);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_ALGORITHM_MINMAX_ELEMENT_HPP
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