162 lines
6.3 KiB
C
162 lines
6.3 KiB
C
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// This file is part of the uSTL library, an STL implementation.
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//
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// Copyright (c) 2005 by Mike Sharov <msharov@users.sourceforge.net>
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// This file is free software, distributed under the MIT License.
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#pragma once
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#include "ualgobase.h"
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namespace ustl {
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/// \brief Returns true if the given range is a heap under \p comp.
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/// A heap is a sequentially encoded binary tree where for every node
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/// comp(node,child1) is false and comp(node,child2) is false.
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/// \ingroup HeapAlgorithms
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/// \ingroup ConditionAlgorithms
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///
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template <typename RandomAccessIterator, typename Compare>
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bool is_heap (RandomAccessIterator first, RandomAccessIterator last, Compare comp)
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{
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RandomAccessIterator iChild (first);
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for (; ++iChild < last; ++first)
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if (comp (*first, *iChild) || (++iChild < last && comp (*first, *iChild)))
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return false;
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return true;
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}
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/// Utility function to "trickle down" the root item - swaps the root item with its
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/// largest child and recursively fixes the proper subtree.
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template <typename RandomAccessIterator, typename Compare>
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void trickle_down_heap (RandomAccessIterator first, size_t iHole, size_t heapSize, Compare comp)
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{
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typedef typename iterator_traits<RandomAccessIterator>::value_type value_type;
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const value_type v (first[iHole]);
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for (size_t iChild; (iChild = 2 * iHole + 1) < heapSize;) {
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if (iChild + 1 < heapSize)
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iChild += comp (first[iChild], first[iChild + 1]);
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if (comp (v, first[iChild])) {
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first[iHole] = first[iChild];
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iHole = iChild;
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} else
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break;
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}
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first[iHole] = v;
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}
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/// \brief make_heap turns the range [first, last) into a heap
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/// At completion, is_heap (first, last, comp) is true.
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/// The algorithm is adapted from "Classic Data Structures in C++" by Timothy Budd.
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/// \ingroup HeapAlgorithms
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/// \ingroup SortingAlgorithms
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///
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template <typename RandomAccessIterator, typename Compare>
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void make_heap (RandomAccessIterator first, RandomAccessIterator last, Compare comp)
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{
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if (last <= first)
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return;
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const size_t heapSize = distance (first, last);
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for (RandomAccessIterator i = first + (heapSize - 1)/2; i >= first; --i)
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trickle_down_heap (first, distance(first,i), heapSize, comp);
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}
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/// \brief Inserts the *--last into the preceeding range assumed to be a heap.
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/// \ingroup HeapAlgorithms
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/// \ingroup MutatingAlgorithms
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template <typename RandomAccessIterator, typename Compare>
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void push_heap (RandomAccessIterator first, RandomAccessIterator last, Compare comp)
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{
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if (last <= first)
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return;
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typedef typename iterator_traits<RandomAccessIterator>::value_type value_type;
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const value_type v (*--last);
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while (first < last) {
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RandomAccessIterator iParent = first + (distance(first, last) - 1) / 2;
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if (comp (v, *iParent))
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break;
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*last = *iParent;
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last = iParent;
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}
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*last = v;
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}
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/// Removes the largest element from the heap (*first) and places it at *(last-1)
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/// [first, last-1) is a heap after this operation.
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/// \ingroup HeapAlgorithms
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/// \ingroup MutatingAlgorithms
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template <typename RandomAccessIterator, typename Compare>
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void pop_heap (RandomAccessIterator first, RandomAccessIterator last, Compare comp)
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{
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if (--last <= first)
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return;
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iter_swap (first, last);
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trickle_down_heap (first, 0, distance(first,last), comp);
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}
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/// Sorts heap [first, last) in descending order according to comp.
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/// \ingroup HeapAlgorithms
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/// \ingroup SortingAlgorithms
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template <typename RandomAccessIterator, typename Compare>
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void sort_heap (RandomAccessIterator first, RandomAccessIterator last, Compare comp)
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{
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for (; first < last; --last)
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pop_heap (first, last, comp);
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}
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#define HEAP_FN_WITH_LESS(rtype, name) \
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template <typename RandomAccessIterator>\
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inline rtype name (RandomAccessIterator first, RandomAccessIterator last) \
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{ \
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typedef typename iterator_traits<RandomAccessIterator>::value_type value_type; \
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return name (first, last, less<value_type>()); \
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}
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HEAP_FN_WITH_LESS (bool, is_heap)
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HEAP_FN_WITH_LESS (void, make_heap)
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HEAP_FN_WITH_LESS (void, push_heap)
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HEAP_FN_WITH_LESS (void, pop_heap)
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HEAP_FN_WITH_LESS (void, sort_heap)
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#undef HEAP_FN_WITH_LESS
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/// \class priority_queue uheap.h ustl.h
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/// \ingroup Sequences
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///
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/// \brief Sorted queue adapter to uSTL containers.
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///
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/// Acts just like the queue adapter, but keeps the elements sorted by priority
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/// specified by the given comparison operator.
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///
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template <typename T, typename Container = vector<T>, typename Comp = less<typename Container::value_type> >
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class priority_queue {
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public:
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typedef Container container_type;
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typedef typename container_type::size_type size_type;
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typedef typename container_type::value_type value_type;
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typedef typename container_type::reference reference;
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typedef typename container_type::const_reference const_reference;
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typedef typename container_type::const_iterator const_iterator;
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public:
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inline explicit priority_queue (const Comp& c = Comp()) : _v(), _c(c) {}
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inline priority_queue (const Comp& c, const container_type& v) : _v(v), _c(c) {}
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priority_queue (const_iterator f, const_iterator l, const Comp& c = Comp())
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: _v(f, l), _c(c) { make_heap (_v.begin(), _v.end(), _c); }
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inline size_type size (void) const { return _v.size(); }
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inline bool empty (void) const { return _v.empty(); }
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inline const_reference top (void) const { return _v.front(); }
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inline void push (const_reference v){ _v.push_back (v); push_heap (_v.begin(), _v.end(), _c); }
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inline void pop (void) { pop_heap (_v.begin(), _v.end()); _v.pop_back(); }
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inline void swap (priority_queue& v){ _v.swap (v._v); swap (_c, v._c); }
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#if HAVE_CPP11
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inline explicit priority_queue (priority_queue&& v) : _v(move(v._v)),_c(v._c) {}
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inline priority_queue (const Comp& c, container_type&& v) : _v(move(v)),_c(c) {}
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priority_queue (const_iterator f, const_iterator l, const Comp& c, container_type&& v)
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: _v(move(v)), _c(c) { _v.insert (_v.end(), f, l); make_heap (_v.begin(), _v.end(), _c); }
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inline priority_queue& operator= (priority_queue&& v) { swap (v); return *this; }
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template <typename... Args>
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inline void emplace (Args&&... args) { _v.emplace_back (forward<Args>(args)...); push_heap (_v.begin(), _v.end(), _c); }
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#endif
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private:
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container_type _v; ///< Element container.
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Comp _c; ///< Comparison functor by value.
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};
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} // namespace ustl
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