... and fix another one.
3 * This file is a part of LEMON, a generic C++ optimization library
5 * Copyright (C) 2003-2006
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
19 #ifndef LEMON_BIN_HEAP_H
20 #define LEMON_BIN_HEAP_H
24 ///\brief Binary Heap implementation.
34 /// A Binary Heap implementation.
36 ///This class implements the \e binary \e heap data structure. A \e heap
37 ///is a data structure for storing items with specified values called \e
38 ///priorities in such a way that finding the item with minimum priority is
39 ///efficient. \c Compare specifies the ordering of the priorities. In a heap
40 ///one can change the priority of an item, add or erase an item, etc.
42 ///\param Item Type of the items to be stored.
43 ///\param Prio Type of the priority of the items.
44 ///\param ItemIntMap A read and writable Item int map, used internally
45 ///to handle the cross references.
46 ///\param Compare A class for the ordering of the priorities. The
47 ///default is \c std::less<Prio>.
51 template <typename Item, typename Prio, typename ItemIntMap,
52 typename Compare = std::less<Prio> >
56 typedef Item ItemType;
57 // FIXME: stl-ben nem ezt hivjak value_type -nak, hanem a kovetkezot...
58 typedef Prio PrioType;
59 typedef std::pair<ItemType,PrioType> PairType;
60 typedef ItemIntMap ItemIntMapType;
61 typedef Compare PrioCompare;
63 /// \brief Type to represent the items states.
65 /// Each Item element have a state associated to it. It may be "in heap",
66 /// "pre heap" or "post heap". The latter two are indifferent from the
67 /// heap's point of view, but may be useful to the user.
69 /// The ItemIntMap \e should be initialized in such way that it maps
70 /// PRE_HEAP (-1) to any element to be put in the heap...
78 std::vector<PairType> data;
83 /// \brief The constructor.
86 /// \param _iim should be given to the constructor, since it is used
87 /// internally to handle the cross references. The value of the map
88 /// should be PRE_HEAP (-1) for each element.
89 explicit BinHeap(ItemIntMap &_iim) : iim(_iim) {}
91 /// \brief The constructor.
94 /// \param _iim should be given to the constructor, since it is used
95 /// internally to handle the cross references. The value of the map
96 /// should be PRE_HEAP (-1) for each element.
98 /// \param _comp The comparator function object.
99 BinHeap(ItemIntMap &_iim, const Compare &_comp)
100 : iim(_iim), comp(_comp) {}
103 /// The number of items stored in the heap.
105 /// \brief Returns the number of items stored in the heap.
106 int size() const { return data.size(); }
108 /// \brief Checks if the heap stores no items.
110 /// Returns \c true if and only if the heap stores no items.
111 bool empty() const { return data.empty(); }
113 /// \brief Make empty this heap.
115 /// Make empty this heap. It does not change the cross reference map.
116 /// If you want to reuse what is not surely empty you should first clear
117 /// the heap and after that you should set the cross reference map for
118 /// each item to \c PRE_HEAP.
124 static int parent(int i) { return (i-1)/2; }
125 static int second_child(int i) { return 2*i+2; }
126 bool less(const PairType &p1, const PairType &p2) const {
127 return comp(p1.second, p2.second);
130 int bubble_up(int hole, PairType p);
131 int bubble_down(int hole, PairType p, int length);
133 void move(const PairType &p, int i) {
139 int n = data.size()-1;
141 iim.set(data[h].first, POST_HEAP);
143 bubble_down(h, data[n], n);
150 /// \brief Insert a pair of item and priority into the heap.
152 /// Adds \c p.first to the heap with priority \c p.second.
153 /// \param p The pair to insert.
154 void push(const PairType &p) {
160 /// \brief Insert an item into the heap with the given heap.
162 /// Adds \c i to the heap with priority \c p.
163 /// \param i The item to insert.
164 /// \param p The priority of the item.
165 void push(const Item &i, const Prio &p) { push(PairType(i,p)); }
167 /// \brief Returns the item with minimum priority relative to \c Compare.
169 /// This method returns the item with minimum priority relative to \c
171 /// \pre The heap must be nonempty.
173 return data[0].first;
176 /// \brief Returns the minimum priority relative to \c Compare.
178 /// It returns the minimum priority relative to \c Compare.
179 /// \pre The heap must be nonempty.
181 return data[0].second;
184 /// \brief Deletes the item with minimum priority relative to \c Compare.
186 /// This method deletes the item with minimum priority relative to \c
187 /// Compare from the heap.
188 /// \pre The heap must be non-empty.
193 /// \brief Deletes \c i from the heap.
195 /// This method deletes item \c i from the heap, if \c i was
196 /// already stored in the heap.
197 /// \param i The item to erase.
198 void erase(const Item &i) {
203 /// \brief Returns the priority of \c i.
205 /// This function returns the priority of item \c i.
206 /// \pre \c i must be in the heap.
207 /// \param i The item.
208 Prio operator[](const Item &i) const {
210 return data[idx].second;
213 /// \brief \c i gets to the heap with priority \c p independently
214 /// if \c i was already there.
216 /// This method calls \ref push(\c i, \c p) if \c i is not stored
217 /// in the heap and sets the priority of \c i to \c p otherwise.
218 /// \param i The item.
219 /// \param p The priority.
220 void set(const Item &i, const Prio &p) {
225 else if( comp(p, data[idx].second) ) {
226 bubble_up(idx, PairType(i,p));
229 bubble_down(idx, PairType(i,p), data.size());
233 /// \brief Decreases the priority of \c i to \c p.
235 /// This method decreases the priority of item \c i to \c p.
236 /// \pre \c i must be stored in the heap with priority at least \c
237 /// p relative to \c Compare.
238 /// \param i The item.
239 /// \param p The priority.
240 void decrease(const Item &i, const Prio &p) {
242 bubble_up(idx, PairType(i,p));
245 /// \brief Increases the priority of \c i to \c p.
247 /// This method sets the priority of item \c i to \c p.
248 /// \pre \c i must be stored in the heap with priority at most \c
249 /// p relative to \c Compare.
250 /// \param i The item.
251 /// \param p The priority.
252 void increase(const Item &i, const Prio &p) {
254 bubble_down(idx, PairType(i,p), data.size());
257 /// \brief Returns if \c item is in, has already been in, or has
258 /// never been in the heap.
260 /// This method returns PRE_HEAP if \c item has never been in the
261 /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
262 /// otherwise. In the latter case it is possible that \c item will
263 /// get back to the heap again.
264 /// \param i The item.
265 state_enum state(const Item &i) const {
269 return state_enum(s);
272 /// \brief Sets the state of the \c item in the heap.
274 /// Sets the state of the \c item in the heap. It can be used to
275 /// manually clear the heap when it is important to achive the
276 /// better time complexity.
277 /// \param i The item.
278 /// \param st The state. It should not be \c IN_HEAP.
279 void state(const Item& i, state_enum st) {
283 if (state(i) == IN_HEAP) {
296 template <typename K, typename V, typename M, typename C>
297 int BinHeap<K,V,M,C>::bubble_up(int hole, PairType p) {
298 int par = parent(hole);
299 while( hole>0 && less(p,data[par]) ) {
300 move(data[par],hole);
308 template <typename K, typename V, typename M, typename C>
309 int BinHeap<K,V,M,C>::bubble_down(int hole, PairType p, int length) {
310 int child = second_child(hole);
311 while(child < length) {
312 if( less(data[child-1], data[child]) ) {
315 if( !less(data[child], p) )
317 move(data[child], hole);
319 child = second_child(hole);
322 if( child<length && less(data[child], p) ) {
323 move(data[child], hole);
334 #endif // LEMON_BIN_HEAP_H