Hmmm...
2 * lemon/bin_heap.h - Part of LEMON, a generic C++ optimization library
4 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
5 * (Egervary Research Group on Combinatorial Optimization, EGRES).
7 * Permission to use, modify and distribute this software is granted
8 * provided that this copyright notice appears in all copies. For
9 * precise terms see the accompanying LICENSE file.
11 * This software is provided "AS IS" with no warranty of any kind,
12 * express or implied, and with no claim as to its suitability for any
17 #ifndef LEMON_BIN_HEAP_H
18 #define LEMON_BIN_HEAP_H
22 ///\brief Binary Heap implementation.
30 /// \addtogroup auxdat
33 /// A Binary Heap implementation.
35 ///This class implements the \e binary \e heap data structure. A \e heap
36 ///is a data structure for storing items with specified values called \e
37 ///priorities in such a way that finding the item with minimum priority is
38 ///efficient. \c Compare specifies the ordering of the priorities. In a heap
39 ///one can change the priority of an item, add or erase an item, etc.
41 ///\param Item Type of the items to be stored.
42 ///\param Prio Type of the priority of the items.
43 ///\param ItemIntMap A read and writable Item int map, used internally
44 ///to handle the cross references.
45 ///\param Compare A class for the ordering of the priorities. The
46 ///default is \c std::less<Prio>.
50 template <typename Item, typename Prio, typename ItemIntMap,
51 typename Compare = std::less<Prio> >
55 typedef Item ItemType;
56 // FIXME: stl-ben nem ezt hivjak value_type -nak, hanem a kovetkezot...
57 typedef Prio PrioType;
58 typedef std::pair<ItemType,PrioType> PairType;
59 typedef ItemIntMap ItemIntMapType;
60 typedef Compare PrioCompare;
62 /// \brief Type to represent the items states.
64 /// Each Item element have a state associated to it. It may be "in heap",
65 /// "pre heap" or "post heap". The latter two are indifferent from the
66 /// heap's point of view, but may be useful to the user.
68 /// The ItemIntMap \e should be initialized in such way that it maps
69 /// PRE_HEAP (-1) to any element to be put in the heap...
77 std::vector<PairType> data;
82 /// \brief The constructor.
85 /// \param _iim should be given to the constructor, since it is used
86 /// internally to handle the cross references. The value of the map
87 /// should be PRE_HEAP (-1) for each element.
88 explicit BinHeap(ItemIntMap &_iim) : iim(_iim) {}
90 /// \brief The constructor.
93 /// \param _iim should be given to the constructor, since it is used
94 /// internally to handle the cross references. The value of the map
95 /// should be PRE_HEAP (-1) for each element.
97 /// \param _comp The comparator function object.
98 BinHeap(ItemIntMap &_iim, const Compare &_comp)
99 : iim(_iim), comp(_comp) {}
102 /// The number of items stored in the heap.
104 /// \brief Returns the number of items stored in the heap.
105 int size() const { return data.size(); }
107 /// \brief Checks if the heap stores no items.
109 /// Returns \c true if and only if the heap stores no items.
110 bool empty() const { return data.empty(); }
113 static int parent(int i) { return (i-1)/2; }
114 static int second_child(int i) { return 2*i+2; }
115 bool less(const PairType &p1, const PairType &p2) const {
116 return comp(p1.second, p2.second);
119 int bubble_up(int hole, PairType p);
120 int bubble_down(int hole, PairType p, int length);
122 void move(const PairType &p, int i) {
128 int n = data.size()-1;
130 iim.set(data[h].first, POST_HEAP);
132 bubble_down(h, data[n], n);
139 /// \brief Insert a pair of item and priority into the heap.
141 /// Adds \c p.first to the heap with priority \c p.second.
142 /// \param p The pair to insert.
143 void push(const PairType &p) {
149 /// \brief Insert an item into the heap with the given heap.
151 /// Adds \c i to the heap with priority \c p.
152 /// \param i The item to insert.
153 /// \param p The priority of the item.
154 void push(const Item &i, const Prio &p) { push(PairType(i,p)); }
156 /// \brief Returns the item with minimum priority relative to \c Compare.
158 /// This method returns the item with minimum priority relative to \c
160 /// \pre The heap must be nonempty.
162 return data[0].first;
165 /// \brief Returns the minimum priority relative to \c Compare.
167 /// It returns the minimum priority relative to \c Compare.
168 /// \pre The heap must be nonempty.
170 return data[0].second;
173 /// \brief Deletes the item with minimum priority relative to \c Compare.
175 /// This method deletes the item with minimum priority relative to \c
176 /// Compare from the heap.
177 /// \pre The heap must be non-empty.
182 /// \brief Deletes \c i from the heap.
184 /// This method deletes item \c i from the heap, if \c i was
185 /// already stored in the heap.
186 /// \param i The item to erase.
187 void erase(const Item &i) {
192 /// \brief Returns the priority of \c i.
194 /// This function returns the priority of item \c i.
195 /// \pre \c i must be in the heap.
196 /// \param i The item.
197 Prio operator[](const Item &i) const {
199 return data[idx].second;
202 /// \brief \c i gets to the heap with priority \c p independently
203 /// if \c i was already there.
205 /// This method calls \ref push(\c i, \c p) if \c i is not stored
206 /// in the heap and sets the priority of \c i to \c p otherwise.
207 /// \param i The item.
208 /// \param p The priority.
209 void set(const Item &i, const Prio &p) {
214 else if( comp(p, data[idx].second) ) {
215 bubble_up(idx, PairType(i,p));
218 bubble_down(idx, PairType(i,p), data.size());
222 /// \brief Decreases the priority of \c i to \c p.
224 /// This method decreases the priority of item \c i to \c p.
225 /// \pre \c i must be stored in the heap with priority at least \c
226 /// p relative to \c Compare.
227 /// \param i The item.
228 /// \param p The priority.
229 void decrease(const Item &i, const Prio &p) {
231 bubble_up(idx, PairType(i,p));
234 /// \brief Increases the priority of \c i to \c p.
236 /// This method sets the priority of item \c i to \c p.
237 /// \pre \c i must be stored in the heap with priority at most \c
238 /// p relative to \c Compare.
239 /// \param i The item.
240 /// \param p The priority.
241 void increase(const Item &i, const Prio &p) {
243 bubble_down(idx, PairType(i,p), data.size());
246 /// \brief Returns if \c item is in, has already been in, or has
247 /// never been in the heap.
249 /// This method returns PRE_HEAP if \c item has never been in the
250 /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
251 /// otherwise. In the latter case it is possible that \c item will
252 /// get back to the heap again.
253 /// \param i The item.
254 state_enum state(const Item &i) const {
258 return state_enum(s);
264 template <typename K, typename V, typename M, typename C>
265 int BinHeap<K,V,M,C>::bubble_up(int hole, PairType p) {
266 int par = parent(hole);
267 while( hole>0 && less(p,data[par]) ) {
268 move(data[par],hole);
276 template <typename K, typename V, typename M, typename C>
277 int BinHeap<K,V,M,C>::bubble_down(int hole, PairType p, int length) {
278 int child = second_child(hole);
279 while(child < length) {
280 if( less(data[child-1], data[child]) ) {
283 if( !less(data[child], p) )
285 move(data[child], hole);
287 child = second_child(hole);
290 if( child<length && less(data[child], p) ) {
291 move(data[child], hole);
303 #endif // LEMON_BIN_HEAP_H