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https://github.com/bolero-MURAKAMI/Sprout.git
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70 lines
2.4 KiB
C++
70 lines
2.4 KiB
C++
#ifndef SPROUT_ALGORITHM_IS_HEAP_UNTIL_HPP
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#define SPROUT_ALGORITHM_IS_HEAP_UNTIL_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 HDR_FUNCTIONAL_SSCRISK_CEL_OR_SPROUT
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namespace sprout {
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namespace detail {
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template<typename RandomAccessIterator, typename Compare>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<RandomAccessIterator>::difference_type
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is_heap_until_impl(
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RandomAccessIterator it, Compare comp,
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typename std::iterator_traits<RandomAccessIterator>::difference_type first, typename std::iterator_traits<RandomAccessIterator>::difference_type last,
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typename std::iterator_traits<RandomAccessIterator>::difference_type pivot, typename std::iterator_traits<RandomAccessIterator>::difference_type found
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)
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{
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return found != first ? found
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: pivot == 0 ? (!comp(it[first], it[(first - 1) / 2]) ? first : last)
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: sprout::detail::is_heap_until_impl(
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it, comp, first + pivot, last,
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((last - first) - pivot) / 2,
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sprout::detail::is_heap_until_impl(
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it, comp, first, first + pivot,
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pivot / 2,
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first
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)
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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 RandomAccessIterator
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is_heap_until_impl(
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RandomAccessIterator first, RandomAccessIterator last, Compare comp,
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typename std::iterator_traits<RandomAccessIterator>::difference_type size
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)
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{
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return size < 2 ? last
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: sprout::next(first, sprout::detail::is_heap_until_impl(first, comp, 1, size, (size - 1) / 2, 1))
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;
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}
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} // namespace detail
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// 25.4.6.5 is_heap
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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 RandomAccessIterator, typename Compare>
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inline SPROUT_CONSTEXPR RandomAccessIterator
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is_heap_until(RandomAccessIterator first, RandomAccessIterator last, Compare comp) {
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return sprout::detail::is_heap_until_impl(
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first, last, comp,
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sprout::distance(first, last)
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);
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}
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template<typename RandomAccessIterator>
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inline SPROUT_CONSTEXPR RandomAccessIterator
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is_heap_until(RandomAccessIterator first, RandomAccessIterator last) {
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return sprout::is_heap_until(
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first, last,
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NS_SSCRISK_CEL_OR_SPROUT::less<typename std::iterator_traits<RandomAccessIterator>::value_type>()
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);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_ALGORITHM_IS_HEAP_UNTIL_HPP
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