Fix template version of Invalid.
2 * lemon/fib_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_FIB_HEAP_H
18 #define LEMON_FIB_HEAP_H
22 ///\brief Fibonacci Heap implementation.
34 ///This class implements the \e Fibonacci \e heap data structure. A \e heap
35 ///is a data structure for storing items with specified values called \e
36 ///priorities in such a way that finding the item with minimum priority is
37 ///efficient. \c Compare specifies the ordering of the priorities. In a heap
38 ///one can change the priority of an item, add or erase an item, etc.
40 ///The methods \ref increase and \ref erase are not efficient in a Fibonacci
41 ///heap. In case of many calls to these operations, it is better to use a
44 ///\param Item Type of the items to be stored.
45 ///\param Prio Type of the priority of the items.
46 ///\param ItemIntMap A read and writable Item int map, used internally
47 ///to handle the cross references.
48 ///\param Compare A class for the ordering of the priorities. The
49 ///default is \c std::less<Prio>.
53 ///\author Jacint Szabo
56 template <typename Item,
61 template <typename Item,
64 typename Compare = std::less<Prio> >
68 typedef Prio PrioType;
73 std::vector<store> container;
80 ///Status of the nodes
82 ///The node is in the heap
84 ///The node has never been in the heap
86 ///The node was in the heap but it got out of it
90 /// \brief The constructor
92 /// \c _iimap should be given to the constructor, since it is
93 /// used internally to handle the cross references.
94 explicit FibHeap(ItemIntMap &_iimap)
95 : minimum(0), iimap(_iimap), num_items() {}
97 /// \brief The constructor
99 /// \c _iimap should be given to the constructor, since it is used
100 /// internally to handle the cross references. \c _comp is an
101 /// object for ordering of the priorities.
102 FibHeap(ItemIntMap &_iimap, const Compare &_comp) : minimum(0),
103 iimap(_iimap), comp(_comp), num_items() {}
105 /// \brief The number of items stored in the heap.
107 /// Returns the number of items stored in the heap.
108 int size() const { return num_items; }
110 /// \brief Checks if the heap stores no items.
112 /// Returns \c true if and only if the heap stores no items.
113 bool empty() const { return num_items==0; }
115 /// \brief Make empty this heap.
117 /// Make empty this heap.
119 if (num_items != 0) {
120 for (int i = 0; i < (int)container.size(); ++i) {
121 iimap[container[i].name] = -2;
124 container.clear(); minimum = 0; num_items = 0;
127 /// \brief \c item gets to the heap with priority \c value independently
128 /// if \c item was already there.
130 /// This method calls \ref push(\c item, \c value) if \c item is not
131 /// stored in the heap and it calls \ref decrease(\c item, \c value) or
132 /// \ref increase(\c item, \c value) otherwise.
133 void set (Item const item, PrioType const value);
135 /// \brief Adds \c item to the heap with priority \c value.
137 /// Adds \c item to the heap with priority \c value.
138 /// \pre \c item must not be stored in the heap.
139 void push (Item const item, PrioType const value);
141 /// \brief Returns the item with minimum priority relative to \c Compare.
143 /// This method returns the item with minimum priority relative to \c
145 /// \pre The heap must be nonempty.
146 Item top() const { return container[minimum].name; }
148 /// \brief Returns the minimum priority relative to \c Compare.
150 /// It returns the minimum priority relative to \c Compare.
151 /// \pre The heap must be nonempty.
152 PrioType prio() const { return container[minimum].prio; }
154 /// \brief Returns the priority of \c item.
156 /// This function returns the priority of \c item.
157 /// \pre \c item must be in the heap.
158 PrioType& operator[](const Item& item) {
159 return container[iimap[item]].prio;
162 /// \brief Returns the priority of \c item.
164 /// It returns the priority of \c item.
165 /// \pre \c item must be in the heap.
166 const PrioType& operator[](const Item& item) const {
167 return container[iimap[item]].prio;
171 /// \brief Deletes the item with minimum priority relative to \c Compare.
173 /// This method deletes the item with minimum priority relative to \c
174 /// Compare from the heap.
175 /// \pre The heap must be non-empty.
178 /// \brief Deletes \c item from the heap.
180 /// This method deletes \c item from the heap, if \c item was already
181 /// stored in the heap. It is quite inefficient in Fibonacci heaps.
182 void erase (const Item& item);
184 /// \brief Decreases the priority of \c item to \c value.
186 /// This method decreases the priority of \c item to \c value.
187 /// \pre \c item must be stored in the heap with priority at least \c
188 /// value relative to \c Compare.
189 void decrease (Item item, PrioType const value);
191 /// \brief Increases the priority of \c item to \c value.
193 /// This method sets the priority of \c item to \c value. Though
194 /// there is no precondition on the priority of \c item, this
195 /// method should be used only if it is indeed necessary to increase
196 /// (relative to \c Compare) the priority of \c item, because this
197 /// method is inefficient.
198 void increase (Item item, PrioType const value) {
204 /// \brief Returns if \c item is in, has already been in, or has never
205 /// been in the heap.
207 /// This method returns PRE_HEAP if \c item has never been in the
208 /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
209 /// otherwise. In the latter case it is possible that \c item will
210 /// get back to the heap again.
211 state_enum state(const Item &item) const {
214 if ( container[i].in ) i=0;
217 return state_enum(i);
223 void makeroot(int c);
224 void cut(int a, int b);
226 void fuse(int a, int b);
231 friend class FibHeap;
243 store() : parent(-1), child(-1), degree(), marked(false), in(true) {}
249 // **********************************************************************
251 // **********************************************************************
253 template <typename Item, typename Prio, typename ItemIntMap,
255 void FibHeap<Item, Prio, ItemIntMap, Compare>::set
256 (Item const item, PrioType const value)
259 if ( i >= 0 && container[i].in ) {
260 if ( comp(value, container[i].prio) ) decrease(item, value);
261 if ( comp(container[i].prio, value) ) increase(item, value);
262 } else push(item, value);
265 template <typename Item, typename Prio, typename ItemIntMap,
267 void FibHeap<Item, Prio, ItemIntMap, Compare>::push
268 (Item const item, PrioType const value) {
271 int s=container.size();
272 iimap.set( item, s );
275 container.push_back(st);
278 container[i].parent=container[i].child=-1;
279 container[i].degree=0;
280 container[i].in=true;
281 container[i].marked=false;
285 container[container[minimum].right_neighbor].left_neighbor=i;
286 container[i].right_neighbor=container[minimum].right_neighbor;
287 container[minimum].right_neighbor=i;
288 container[i].left_neighbor=minimum;
289 if ( comp( value, container[minimum].prio) ) minimum=i;
291 container[i].right_neighbor=container[i].left_neighbor=i;
294 container[i].prio=value;
298 template <typename Item, typename Prio, typename ItemIntMap,
300 void FibHeap<Item, Prio, ItemIntMap, Compare>::pop() {
301 /*The first case is that there are only one root.*/
302 if ( container[minimum].left_neighbor==minimum ) {
303 container[minimum].in=false;
304 if ( container[minimum].degree!=0 ) {
305 makeroot(container[minimum].child);
306 minimum=container[minimum].child;
310 int right=container[minimum].right_neighbor;
312 container[minimum].in=false;
313 if ( container[minimum].degree > 0 ) {
314 int left=container[minimum].left_neighbor;
315 int child=container[minimum].child;
316 int last_child=container[child].left_neighbor;
320 container[left].right_neighbor=child;
321 container[child].left_neighbor=left;
322 container[right].left_neighbor=last_child;
323 container[last_child].right_neighbor=right;
327 } // the case where there are more roots
332 template <typename Item, typename Prio, typename ItemIntMap,
334 void FibHeap<Item, Prio, ItemIntMap, Compare>::erase
338 if ( i >= 0 && container[i].in ) {
339 if ( container[i].parent!=-1 ) {
340 int p=container[i].parent;
344 minimum=i; //As if its prio would be -infinity
349 template <typename Item, typename Prio, typename ItemIntMap,
351 void FibHeap<Item, Prio, ItemIntMap, Compare>::decrease
352 (Item item, PrioType const value) {
354 container[i].prio=value;
355 int p=container[i].parent;
357 if ( p!=-1 && comp(value, container[p].prio) ) {
361 if ( comp(value, container[minimum].prio) ) minimum=i;
365 template <typename Item, typename Prio, typename ItemIntMap,
367 void FibHeap<Item, Prio, ItemIntMap, Compare>::balance() {
369 int maxdeg=int( std::floor( 2.08*log(double(container.size()))))+1;
371 std::vector<int> A(maxdeg,-1);
374 *Recall that now minimum does not point to the minimum prio element.
375 *We set minimum to this during balance().
377 int anchor=container[minimum].left_neighbor;
383 if ( anchor==active ) end=true;
384 int d=container[active].degree;
385 next=container[active].right_neighbor;
388 if( comp(container[active].prio, container[A[d]].prio) ) {
401 while ( container[minimum].parent >=0 ) minimum=container[minimum].parent;
405 if ( comp(container[s].prio, container[minimum].prio) ) minimum=s;
406 s=container[s].right_neighbor;
410 template <typename Item, typename Prio, typename ItemIntMap,
412 void FibHeap<Item, Prio, ItemIntMap, Compare>::makeroot
416 container[s].parent=-1;
417 s=container[s].right_neighbor;
422 template <typename Item, typename Prio, typename ItemIntMap,
424 void FibHeap<Item, Prio, ItemIntMap, Compare>::cut
427 *Replacing a from the children of b.
429 --container[b].degree;
431 if ( container[b].degree !=0 ) {
432 int child=container[b].child;
434 container[b].child=container[child].right_neighbor;
439 /*Lacing a to the roots.*/
440 int right=container[minimum].right_neighbor;
441 container[minimum].right_neighbor=a;
442 container[a].left_neighbor=minimum;
443 container[a].right_neighbor=right;
444 container[right].left_neighbor=a;
446 container[a].parent=-1;
447 container[a].marked=false;
451 template <typename Item, typename Prio, typename ItemIntMap,
453 void FibHeap<Item, Prio, ItemIntMap, Compare>::cascade
456 if ( container[a].parent!=-1 ) {
457 int p=container[a].parent;
459 if ( container[a].marked==false ) container[a].marked=true;
468 template <typename Item, typename Prio, typename ItemIntMap,
470 void FibHeap<Item, Prio, ItemIntMap, Compare>::fuse
474 /*Lacing b under a.*/
475 container[b].parent=a;
477 if (container[a].degree==0) {
478 container[b].left_neighbor=b;
479 container[b].right_neighbor=b;
480 container[a].child=b;
482 int child=container[a].child;
483 int last_child=container[child].left_neighbor;
484 container[child].left_neighbor=b;
485 container[b].right_neighbor=child;
486 container[last_child].right_neighbor=b;
487 container[b].left_neighbor=last_child;
490 ++container[a].degree;
492 container[b].marked=false;
497 *It is invoked only if a has siblings.
499 template <typename Item, typename Prio, typename ItemIntMap,
501 void FibHeap<Item, Prio, ItemIntMap, Compare>::unlace
503 int leftn=container[a].left_neighbor;
504 int rightn=container[a].right_neighbor;
505 container[leftn].right_neighbor=rightn;
506 container[rightn].left_neighbor=leftn;
512 #endif //LEMON_FIB_HEAP_H