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42 lines
1.3 KiB
C++
42 lines
1.3 KiB
C++
#ifndef SPROUT_ALGORITHM_PARTITION_POINT_HPP
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#define SPROUT_ALGORITHM_PARTITION_POINT_HPP
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#include <sprout/config.hpp>
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#include <sprout/iterator/operation.hpp>
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namespace sprout {
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// Copyright (C) 2011 RiSK (sscrisk)
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namespace detail {
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template<typename ForwardIterator, typename Predicate>
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inline SPROUT_CONSTEXPR ForwardIterator
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partition_point_impl(ForwardIterator first, ForwardIterator last, Predicate pred, ForwardIterator mid) {
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return mid == last ? mid
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: pred(*mid) ? sprout::detail::partition_point_impl(
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sprout::next(mid), last, pred,
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sprout::next(mid, 1 + (sprout::distance(mid, last) - 1) / 2)
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)
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: sprout::detail::partition_point_impl(
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first, mid, pred,
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sprout::next(first, sprout::distance(first, mid) / 2)
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)
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;
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}
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} // namespace detail
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// 25.3.13 Partitions
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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 Predicate>
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inline SPROUT_CONSTEXPR ForwardIterator
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partition_point(ForwardIterator first, ForwardIterator last, Predicate pred) {
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return sprout::detail::partition_point_impl(
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first, last, pred,
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sprout::next(first, sprout::distance(first, last) / 2)
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);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_ALGORITHM_PARTITION_POINT_HPP
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