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https://github.com/bolero-MURAKAMI/Sprout.git
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106 lines
3.9 KiB
C++
106 lines
3.9 KiB
C++
#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 <sprout/config.hpp>
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#include <sprout/iterator/operation.hpp>
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#include <sprout/utility/pair.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 InputIteratorPair, typename Compare>
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inline SPROUT_CONSTEXPR InputIteratorPair
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iter_minmax(InputIteratorPair a, InputIteratorPair b, Compare comp) {
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return InputIteratorPair(
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comp(*sprout::first(b), *sprout::first(a)) ? sprout::first(b) : sprout::first(a),
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comp(*sprout::second(a), *sprout::second(b)) ? sprout::second(b) : sprout::second(a)
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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 first, RandomAccessIterator last, Compare comp,
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typename std::iterator_traits<RandomAccessIterator>::difference_type pivot
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)
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{
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return pivot == 0 ? sprout::pair<RandomAccessIterator, RandomAccessIterator>(first, first)
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: sprout::detail::iter_minmax(
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sprout::detail::minmax_element_impl_ra(
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first, sprout::next(first, pivot), comp,
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pivot / 2
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),
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sprout::detail::minmax_element_impl_ra(
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sprout::next(first, pivot), last, comp,
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(sprout::distance(first, last) - pivot) / 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 sprout::pair<RandomAccessIterator, RandomAccessIterator>
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minmax_element(
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RandomAccessIterator first, RandomAccessIterator 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::pair<RandomAccessIterator, RandomAccessIterator>(last, last)
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: sprout::detail::minmax_element_impl_ra(
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first, last, comp,
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sprout::distance(first, last) / 2
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)
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;
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}
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// Copyright (C) 2011 RiSK (sscrisk)
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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_impl(
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ForwardIterator first, ForwardIterator last, Compare comp,
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ForwardIterator min, ForwardIterator max
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)
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{
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return first == last ? sprout::pair<ForwardIterator, ForwardIterator>(min, max)
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: comp(*first, *min) ? sprout::detail::minmax_element_impl(sprout::next(first), last, comp, first, max)
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: sprout::detail::minmax_element_impl(sprout::next(first), last, comp, min, comp(*first, *max) ? max : first)
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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 first, ForwardIterator last, Compare comp,
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void*
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)
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{
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return first == last ? sprout::pair<ForwardIterator, ForwardIterator>(last, last)
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: sprout::detail::minmax_element_impl(sprout::next(first), last, comp, first, first)
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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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// [first, last) is RandomAccessIterator -> O(log N)
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// otherwise -> O(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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