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53 lines
1.9 KiB
C++
53 lines
1.9 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2013 Bolero MURAKAMI
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Copyright (C) 2011 RiSK (sscrisk)
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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_LOWER_BOUND_HPP
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#define SPROUT_ALGORITHM_LOWER_BOUND_HPP
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#include <iterator>
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#include <sprout/config.hpp>
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#include <sprout/iterator/next.hpp>
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#include <sprout/iterator/distance.hpp>
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#include <sprout/functional/less.hpp>
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namespace sprout {
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namespace detail {
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template<typename ForwardIterator, typename T, typename Compare>
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inline SPROUT_CONSTEXPR ForwardIterator
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lower_bound(
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ForwardIterator first, typename std::iterator_traits<ForwardIterator>::difference_type len,
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T const& value, Compare comp
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)
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{
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return len == 0 ? first
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: comp(*sprout::next(first, len / 2), value)
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? sprout::detail::lower_bound(sprout::next(first, len / 2 + 1), len - (len / 2 + 1), value, comp)
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: sprout::detail::lower_bound(first, len / 2, value, comp)
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;
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}
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} // namespace detail
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// 25.4.3.1 lower_bound
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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 T, typename Compare>
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inline SPROUT_CONSTEXPR ForwardIterator
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lower_bound(ForwardIterator first, ForwardIterator last, T const& value, Compare comp) {
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return sprout::detail::lower_bound(first, sprout::distance(first, last), value, comp);
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}
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template<typename ForwardIterator, typename T>
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inline SPROUT_CONSTEXPR ForwardIterator
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lower_bound(ForwardIterator first, ForwardIterator last, T const& value) {
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return sprout::lower_bound(first, last, value, sprout::less<>());
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_ALGORITHM_LOWER_BOUND_HPP
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