Use only a single (cached) variable to hold the version number.
1 /* -*- mode: C++; indent-tabs-mode: nil; -*-
3 * This file is a part of LEMON, a generic C++ optimization library.
5 * Copyright (C) 2003-2008
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 ///\brief 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 ///\tparam _Prio Type of the priority of the items.
43 ///\tparam _ItemIntMap A read and writable Item int map, used internally
44 ///to handle the cross references.
45 ///\tparam _Compare A class for the ordering of the priorities. The
46 ///default is \c std::less<_Prio>.
50 template <typename _Prio, typename _ItemIntMap,
51 typename _Compare = std::less<_Prio> >
56 typedef _ItemIntMap ItemIntMap;
60 typedef typename ItemIntMap::Key Item;
62 typedef std::pair<Item,Prio> Pair;
64 typedef _Compare Compare;
66 /// \brief Type to represent the items states.
68 /// Each Item element have a state associated to it. It may be "in heap",
69 /// "pre heap" or "post heap". The latter two are indifferent from the
70 /// heap's point of view, but may be useful to the user.
72 /// The ItemIntMap \e should be initialized in such way that it maps
73 /// PRE_HEAP (-1) to any element to be put in the heap...
81 std::vector<Pair> data;
86 /// \brief The constructor.
89 /// \param _iim should be given to the constructor, since it is used
90 /// internally to handle the cross references. The value of the map
91 /// should be PRE_HEAP (-1) for each element.
92 explicit BinHeap(ItemIntMap &_iim) : iim(_iim) {}
94 /// \brief The constructor.
97 /// \param _iim should be given to the constructor, since it is used
98 /// internally to handle the cross references. The value of the map
99 /// should be PRE_HEAP (-1) for each element.
101 /// \param _comp The comparator function object.
102 BinHeap(ItemIntMap &_iim, const Compare &_comp)
103 : iim(_iim), comp(_comp) {}
106 /// The number of items stored in the heap.
108 /// \brief Returns the number of items stored in the heap.
109 int size() const { return data.size(); }
111 /// \brief Checks if the heap stores no items.
113 /// Returns \c true if and only if the heap stores no items.
114 bool empty() const { return data.empty(); }
116 /// \brief Make empty this heap.
118 /// Make empty this heap. It does not change the cross reference map.
119 /// If you want to reuse what is not surely empty you should first clear
120 /// the heap and after that you should set the cross reference map for
121 /// each item to \c PRE_HEAP.
127 static int parent(int i) { return (i-1)/2; }
129 static int second_child(int i) { return 2*i+2; }
130 bool less(const Pair &p1, const Pair &p2) const {
131 return comp(p1.second, p2.second);
134 int bubble_up(int hole, Pair p) {
135 int par = parent(hole);
136 while( hole>0 && less(p,data[par]) ) {
137 move(data[par],hole);
145 int bubble_down(int hole, Pair p, int length) {
146 int child = second_child(hole);
147 while(child < length) {
148 if( less(data[child-1], data[child]) ) {
151 if( !less(data[child], p) )
153 move(data[child], hole);
155 child = second_child(hole);
158 if( child<length && less(data[child], p) ) {
159 move(data[child], hole);
167 void move(const Pair &p, int i) {
173 /// \brief Insert a pair of item and priority into the heap.
175 /// Adds \c p.first to the heap with priority \c p.second.
176 /// \param p The pair to insert.
177 void push(const Pair &p) {
183 /// \brief Insert an item into the heap with the given heap.
185 /// Adds \c i to the heap with priority \c p.
186 /// \param i The item to insert.
187 /// \param p The priority of the item.
188 void push(const Item &i, const Prio &p) { push(Pair(i,p)); }
190 /// \brief Returns the item with minimum priority relative to \c Compare.
192 /// This method returns the item with minimum priority relative to \c
194 /// \pre The heap must be nonempty.
196 return data[0].first;
199 /// \brief Returns the minimum priority relative to \c Compare.
201 /// It returns the minimum priority relative to \c Compare.
202 /// \pre The heap must be nonempty.
204 return data[0].second;
207 /// \brief Deletes the item with minimum priority relative to \c Compare.
209 /// This method deletes the item with minimum priority relative to \c
210 /// Compare from the heap.
211 /// \pre The heap must be non-empty.
213 int n = data.size()-1;
214 iim.set(data[0].first, POST_HEAP);
216 bubble_down(0, data[n], n);
221 /// \brief Deletes \c i from the heap.
223 /// This method deletes item \c i from the heap.
224 /// \param i The item to erase.
225 /// \pre The item should be in the heap.
226 void erase(const Item &i) {
228 int n = data.size()-1;
229 iim.set(data[h].first, POST_HEAP);
231 if ( bubble_up(h, data[n]) == h) {
232 bubble_down(h, data[n], n);
239 /// \brief Returns the priority of \c i.
241 /// This function returns the priority of item \c i.
242 /// \pre \c i must be in the heap.
243 /// \param i The item.
244 Prio operator[](const Item &i) const {
246 return data[idx].second;
249 /// \brief \c i gets to the heap with priority \c p independently
250 /// if \c i was already there.
252 /// This method calls \ref push(\c i, \c p) if \c i is not stored
253 /// in the heap and sets the priority of \c i to \c p otherwise.
254 /// \param i The item.
255 /// \param p The priority.
256 void set(const Item &i, const Prio &p) {
261 else if( comp(p, data[idx].second) ) {
262 bubble_up(idx, Pair(i,p));
265 bubble_down(idx, Pair(i,p), data.size());
269 /// \brief Decreases the priority of \c i to \c p.
271 /// This method decreases the priority of item \c i to \c p.
272 /// \pre \c i must be stored in the heap with priority at least \c
273 /// p relative to \c Compare.
274 /// \param i The item.
275 /// \param p The priority.
276 void decrease(const Item &i, const Prio &p) {
278 bubble_up(idx, Pair(i,p));
281 /// \brief Increases the priority of \c i to \c p.
283 /// This method sets the priority of item \c i to \c p.
284 /// \pre \c i must be stored in the heap with priority at most \c
285 /// p relative to \c Compare.
286 /// \param i The item.
287 /// \param p The priority.
288 void increase(const Item &i, const Prio &p) {
290 bubble_down(idx, Pair(i,p), data.size());
293 /// \brief Returns if \c item is in, has already been in, or has
294 /// never been in the heap.
296 /// This method returns PRE_HEAP if \c item has never been in the
297 /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
298 /// otherwise. In the latter case it is possible that \c item will
299 /// get back to the heap again.
300 /// \param i The item.
301 State state(const Item &i) const {
308 /// \brief Sets the state of the \c item in the heap.
310 /// Sets the state of the \c item in the heap. It can be used to
311 /// manually clear the heap when it is important to achive the
312 /// better time complexity.
313 /// \param i The item.
314 /// \param st The state. It should not be \c IN_HEAP.
315 void state(const Item& i, State st) {
319 if (state(i) == IN_HEAP) {
329 /// \brief Replaces an item in the heap.
331 /// The \c i item is replaced with \c j item. The \c i item should
332 /// be in the heap, while the \c j should be out of the heap. The
333 /// \c i item will out of the heap and \c j will be in the heap
334 /// with the same prioriority as prevoiusly the \c i item.
335 void replace(const Item& i, const Item& j) {
346 #endif // LEMON_BIN_HEAP_H