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Sprout/sprout/algorithm/lower_bound.hpp
2013-08-31 08:29:24 +09:00

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1.6 KiB
C++

/*=============================================================================
Copyright (c) 2011-2013 Bolero MURAKAMI
Copyright (C) 2011 RiSK (sscrisk)
https://github.com/bolero-MURAKAMI/Sprout
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef SPROUT_ALGORITHM_LOWER_BOUND_HPP
#define SPROUT_ALGORITHM_LOWER_BOUND_HPP
#include <iterator>
#include <sprout/config.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/functional/less.hpp>
namespace sprout {
// 25.4.3.1 lower_bound
//
// recursion depth:
// O(log N)
//
template<typename ForwardIterator, typename T, typename Compare>
inline SPROUT_CONSTEXPR ForwardIterator
lower_bound(ForwardIterator first, ForwardIterator last, T const& value, Compare comp) {
return first == last ? last
: sprout::next(first) == last ? comp(*first, value) ? last : first
: comp(*sprout::next(first, sprout::distance(first, last) / 2), value)
? sprout::lower_bound(sprout::next(first, sprout::distance(first, last) / 2 + 1), last, value, comp)
: sprout::lower_bound(first, sprout::next(first, sprout::distance(first, last) / 2), value, comp)
;
}
template<typename ForwardIterator, typename T>
inline SPROUT_CONSTEXPR ForwardIterator
lower_bound(ForwardIterator first, ForwardIterator last, T const& value) {
return sprout::lower_bound(first, last, value, sprout::less<>());
}
} // namespace sprout
#endif // #ifndef SPROUT_ALGORITHM_LOWER_BOUND_HPP