441 lines
15 KiB
C++
441 lines
15 KiB
C++
/// \file
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// Range v3 library
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//
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// Copyright Eric Niebler 2014-present
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//
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// Use, modification and distribution is subject to the
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// Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// Project home: https://github.com/ericniebler/range-v3
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//
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//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef RANGES_V3_ALGORITHM_HEAP_ALGORITHM_HPP
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#define RANGES_V3_ALGORITHM_HEAP_ALGORITHM_HPP
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#include <functional>
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#include <meta/meta.hpp>
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#include <range/v3/range_fwd.hpp>
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#include <range/v3/functional/comparisons.hpp>
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#include <range/v3/functional/identity.hpp>
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#include <range/v3/functional/invoke.hpp>
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#include <range/v3/iterator/concepts.hpp>
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#include <range/v3/iterator/operations.hpp>
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#include <range/v3/iterator/traits.hpp>
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#include <range/v3/range/access.hpp>
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#include <range/v3/range/concepts.hpp>
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#include <range/v3/range/dangling.hpp>
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#include <range/v3/range/traits.hpp>
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#include <range/v3/utility/static_const.hpp>
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#include <range/v3/detail/prologue.hpp>
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namespace ranges
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{
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/// \cond
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namespace detail
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{
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struct is_heap_until_n_fn
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{
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template(typename I, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_iterator<I> AND
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indirect_strict_weak_order<C, projected<I, P>>)
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I operator()(I const begin_, iter_difference_t<I> const n_, C pred = C{},
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P proj = P{}) const
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{
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RANGES_EXPECT(0 <= n_);
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iter_difference_t<I> p = 0, c = 1;
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I pp = begin_;
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while(c < n_)
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{
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I cp = begin_ + c;
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if(invoke(pred, invoke(proj, *pp), invoke(proj, *cp)))
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return cp;
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++c;
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++cp;
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if(c == n_ || invoke(pred, invoke(proj, *pp), invoke(proj, *cp)))
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return cp;
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++p;
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++pp;
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c = 2 * p + 1;
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}
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return begin_ + n_;
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}
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};
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RANGES_INLINE_VARIABLE(is_heap_until_n_fn, is_heap_until_n)
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struct is_heap_n_fn
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{
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template(typename I, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_iterator<I> AND
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indirect_strict_weak_order<C, projected<I, P>>)
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bool operator()(I first, iter_difference_t<I> n, C pred = C{},
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P proj = P{}) const
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{
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return is_heap_until_n(first, n, std::move(pred), std::move(proj)) ==
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first + n;
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}
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};
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RANGES_INLINE_VARIABLE(is_heap_n_fn, is_heap_n)
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} // namespace detail
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/// \endcond
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/// \addtogroup group-algorithms
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/// @{
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RANGES_FUNC_BEGIN(is_heap_until)
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/// \brief function template \c is_heap_until
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template(typename I, typename S, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_iterator<I> AND sentinel_for<S, I> AND
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indirect_strict_weak_order<C, projected<I, P>>)
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I RANGES_FUNC(is_heap_until)(I first, S last, C pred = C{}, P proj = P{})
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{
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return detail::is_heap_until_n(std::move(first),
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distance(first, last),
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std::move(pred),
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std::move(proj));
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}
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/// \overload
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template(typename Rng, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_range<Rng> AND
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indirect_strict_weak_order<C, projected<iterator_t<Rng>, P>>)
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borrowed_iterator_t<Rng> //
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RANGES_FUNC(is_heap_until)(Rng && rng, C pred = C{}, P proj = P{})
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{
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return detail::is_heap_until_n(
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begin(rng), distance(rng), std::move(pred), std::move(proj));
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}
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RANGES_FUNC_END(is_heap_until)
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namespace cpp20
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{
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using ranges::is_heap_until;
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}
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RANGES_FUNC_BEGIN(is_heap)
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/// \brief function template \c is_heap
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template(typename I, typename S, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_iterator<I> AND sentinel_for<S, I> AND
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indirect_strict_weak_order<C, projected<I, P>>)
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bool RANGES_FUNC(is_heap)(I first, S last, C pred = C{}, P proj = P{}) //
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{
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return detail::is_heap_n(std::move(first),
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distance(first, last),
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std::move(pred),
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std::move(proj));
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}
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/// \overload
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template(typename Rng, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_range<Rng> AND
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indirect_strict_weak_order<C, projected<iterator_t<Rng>, P>>)
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bool RANGES_FUNC(is_heap)(Rng && rng, C pred = C{}, P proj = P{}) //
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{
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return detail::is_heap_n(
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begin(rng), distance(rng), std::move(pred), std::move(proj));
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}
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RANGES_FUNC_END(is_heap)
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namespace cpp20
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{
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using ranges::is_heap;
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}
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/// @}
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/// \cond
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namespace detail
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{
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struct sift_up_n_fn
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{
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template<typename I, typename C = less, typename P = identity>
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void operator()(I first, iter_difference_t<I> len, C pred = C{},
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P proj = P{}) const
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{
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if(len > 1)
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{
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I last = first + len;
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len = (len - 2) / 2;
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I i = first + len;
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if(invoke(pred, invoke(proj, *i), invoke(proj, *--last)))
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{
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iter_value_t<I> v = iter_move(last);
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do
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{
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*last = iter_move(i);
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last = i;
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if(len == 0)
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break;
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len = (len - 1) / 2;
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i = first + len;
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} while(invoke(pred, invoke(proj, *i), invoke(proj, v)));
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*last = std::move(v);
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}
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}
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}
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};
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RANGES_INLINE_VARIABLE(sift_up_n_fn, sift_up_n)
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struct sift_down_n_fn
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{
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template<typename I, typename C = less, typename P = identity>
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void operator()(I first, iter_difference_t<I> len, I start, C pred = C{},
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P proj = P{}) const
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{
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// left-child of start is at 2 * start + 1
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// right-child of start is at 2 * start + 2
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auto child = start - first;
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if(len < 2 || (len - 2) / 2 < child)
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return;
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child = 2 * child + 1;
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I child_i = first + child;
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if((child + 1) < len &&
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invoke(pred, invoke(proj, *child_i), invoke(proj, *(child_i + 1))))
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{
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// right-child exists and is greater than left-child
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++child_i;
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++child;
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}
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// check if we are in heap-order
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if(invoke(pred, invoke(proj, *child_i), invoke(proj, *start)))
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// we are, start is larger than it's largest child
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return;
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iter_value_t<I> top = iter_move(start);
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do
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{
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// we are not in heap-order, swap the parent with it's largest child
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*start = iter_move(child_i);
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start = child_i;
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if((len - 2) / 2 < child)
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break;
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// recompute the child based off of the updated parent
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child = 2 * child + 1;
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child_i = first + child;
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if((child + 1) < len &&
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invoke(pred, invoke(proj, *child_i), invoke(proj, *(child_i + 1))))
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{
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// right-child exists and is greater than left-child
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++child_i;
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++child;
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}
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// check if we are in heap-order
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} while(!invoke(pred, invoke(proj, *child_i), invoke(proj, top)));
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*start = std::move(top);
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}
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};
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RANGES_INLINE_VARIABLE(sift_down_n_fn, sift_down_n)
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} // namespace detail
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/// \endcond
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/// \addtogroup group-algorithms
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/// @{
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RANGES_FUNC_BEGIN(push_heap)
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/// \brief function template \c push_heap
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template(typename I, typename S, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_iterator<I> AND sentinel_for<S, I> AND
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sortable<I, C, P>)
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I RANGES_FUNC(push_heap)(I first, S last, C pred = C{}, P proj = P{})
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{
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auto n = distance(first, last);
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detail::sift_up_n(first, n, std::move(pred), std::move(proj));
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return first + n;
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}
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/// \overload
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template(typename Rng, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_range<Rng> AND sortable<iterator_t<Rng>, C, P>)
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borrowed_iterator_t<Rng> //
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RANGES_FUNC(push_heap)(Rng && rng, C pred = C{}, P proj = P{}) //
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{
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iterator_t<Rng> first = ranges::begin(rng);
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auto n = distance(rng);
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detail::sift_up_n(first, n, std::move(pred), std::move(proj));
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return first + n;
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}
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RANGES_FUNC_END(push_heap)
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namespace cpp20
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{
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using ranges::push_heap;
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}
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/// @}
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/// \cond
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namespace detail
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{
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struct pop_heap_n_fn
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{
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template(typename I, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_iterator<I> AND sortable<I, C, P>)
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void operator()(I first, iter_difference_t<I> len, C pred = C{},
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P proj = P{}) const
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{
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if(len > 1)
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{
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ranges::iter_swap(first, first + (len - 1));
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detail::sift_down_n(
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first, len - 1, first, std::move(pred), std::move(proj));
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}
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}
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};
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RANGES_INLINE_VARIABLE(pop_heap_n_fn, pop_heap_n)
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} // namespace detail
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/// \endcond
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/// \addtogroup group-algorithms
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/// @{
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RANGES_FUNC_BEGIN(pop_heap)
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/// \brief function template \c pop_heap
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template(typename I, typename S, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_iterator<I> AND sentinel_for<S, I> AND
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sortable<I, C, P>)
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I RANGES_FUNC(pop_heap)(I first, S last, C pred = C{}, P proj = P{})
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{
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auto n = distance(first, last);
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detail::pop_heap_n(first, n, std::move(pred), std::move(proj));
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return first + n;
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}
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/// \overload
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template(typename Rng, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_range<Rng> AND sortable<iterator_t<Rng>, C, P>)
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borrowed_iterator_t<Rng> //
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RANGES_FUNC(pop_heap)(Rng && rng, C pred = C{}, P proj = P{})
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{
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iterator_t<Rng> first = ranges::begin(rng);
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auto n = distance(rng);
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detail::pop_heap_n(first, n, std::move(pred), std::move(proj));
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return first + n;
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}
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RANGES_FUNC_END(pop_heap)
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namespace cpp20
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{
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using ranges::pop_heap;
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}
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RANGES_FUNC_BEGIN(make_heap)
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/// \brief function template \c make_heap
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template(typename I, typename S, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_iterator<I> AND sentinel_for<S, I> AND
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sortable<I, C, P>)
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I RANGES_FUNC(make_heap)(I first, S last, C pred = C{}, P proj = P{})
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{
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iter_difference_t<I> const n = distance(first, last);
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if(n > 1)
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// start from the first parent, there is no need to consider children
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for(auto start = (n - 2) / 2; start >= 0; --start)
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detail::sift_down_n(
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first, n, first + start, std::ref(pred), std::ref(proj));
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return first + n;
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}
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/// \overload
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template(typename Rng, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_range<Rng> AND sortable<iterator_t<Rng>, C, P>)
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borrowed_iterator_t<Rng> //
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RANGES_FUNC(make_heap)(Rng && rng, C pred = C{}, P proj = P{})
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{
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iterator_t<Rng> first = ranges::begin(rng);
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auto const n = distance(rng);
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if(n > 1)
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// start from the first parent, there is no need to consider children
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for(auto start = (n - 2) / 2; start >= 0; --start)
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detail::sift_down_n(
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first, n, first + start, std::ref(pred), std::ref(proj));
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return first + n;
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}
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RANGES_FUNC_END(make_heap)
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namespace cpp20
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{
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using ranges::make_heap;
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}
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RANGES_FUNC_BEGIN(sort_heap)
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template(typename I, typename S, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_iterator<I> AND sentinel_for<S, I> AND
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sortable<I, C, P>)
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I RANGES_FUNC(sort_heap)(I first, S last, C pred = C{}, P proj = P{})
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{
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iter_difference_t<I> const n = distance(first, last);
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for(auto i = n; i > 1; --i)
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detail::pop_heap_n(first, i, std::ref(pred), std::ref(proj));
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return first + n;
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}
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template(typename Rng, typename C = less, typename P = identity)(
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/// \pre
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requires random_access_range<Rng &> AND sortable<iterator_t<Rng>, C, P>)
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borrowed_iterator_t<Rng> //
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RANGES_FUNC(sort_heap)(Rng && rng, C pred = C{}, P proj = P{})
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{
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iterator_t<Rng> first = ranges::begin(rng);
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auto const n = distance(rng);
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for(auto i = n; i > 1; --i)
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detail::pop_heap_n(first, i, std::ref(pred), std::ref(proj));
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return first + n;
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}
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RANGES_FUNC_END(sort_heap)
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namespace cpp20
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{
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using ranges::sort_heap;
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}
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/// @}
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} // namespace ranges
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#include <range/v3/detail/epilogue.hpp>
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#endif
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