diff --git a/lemon/binom_heap.h b/lemon/binom_heap.h new file mode 100644 --- /dev/null +++ b/lemon/binom_heap.h @@ -0,0 +1,506 @@ +/* -*- C++ -*- + * + * This file is a part of LEMON, a generic C++ optimization library + * + * Copyright (C) 2003-2008 + * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport + * (Egervary Research Group on Combinatorial Optimization, EGRES). + * + * Permission to use, modify and distribute this software is granted + * provided that this copyright notice appears in all copies. For + * precise terms see the accompanying LICENSE file. + * + * This software is provided "AS IS" with no warranty of any kind, + * express or implied, and with no claim as to its suitability for any + * purpose. + * + */ + +#ifndef LEMON_BINOM_HEAP_H +#define LEMON_BINOM_HEAP_H + +///\file +///\ingroup auxdat +///\brief Binomial Heap implementation. + +#include +#include +#include +#include + +namespace lemon { + + /// \ingroup auxdat + /// + ///\brief Binomial Heap. + /// + ///This class implements the \e Binomial \e heap data structure. A \e heap + ///is a data structure for storing items with specified values called \e + ///priorities in such a way that finding the item with minimum priority is + ///efficient. \c Compare specifies the ordering of the priorities. In a heap + ///one can change the priority of an item, add or erase an item, etc. + /// + ///The methods \ref increase and \ref erase are not efficient in a Binomial + ///heap. In case of many calls to these operations, it is better to use a + ///\ref BinHeap "binary heap". + /// + ///\param _Prio Type of the priority of the items. + ///\param _ItemIntMap A read and writable Item int map, used internally + ///to handle the cross references. + ///\param _Compare A class for the ordering of the priorities. The + ///default is \c std::less<_Prio>. + /// + ///\sa BinHeap + ///\sa Dijkstra + ///\author Dorian Batha + +#ifdef DOXYGEN + template +#else + template > +#endif + class BinomHeap { + public: + typedef _ItemIntMap ItemIntMap; + typedef _Prio Prio; + typedef typename ItemIntMap::Key Item; + typedef std::pair Pair; + typedef _Compare Compare; + + private: + class store; + + std::vector container; + int minimum, head; + ItemIntMap &iimap; + Compare comp; + int num_items; + + public: + ///Status of the nodes + enum State { + ///The node is in the heap + IN_HEAP = 0, + ///The node has never been in the heap + PRE_HEAP = -1, + ///The node was in the heap but it got out of it + POST_HEAP = -2 + }; + + /// \brief The constructor + /// + /// \c _iimap should be given to the constructor, since it is + /// used internally to handle the cross references. + explicit BinomHeap(ItemIntMap &_iimap) + : minimum(0), head(-1), iimap(_iimap), num_items() {} + + /// \brief The constructor + /// + /// \c _iimap should be given to the constructor, since it is used + /// internally to handle the cross references. \c _comp is an + /// object for ordering of the priorities. + BinomHeap(ItemIntMap &_iimap, const Compare &_comp) + : minimum(0), head(-1), iimap(_iimap), comp(_comp), num_items() {} + + /// \brief The number of items stored in the heap. + /// + /// Returns the number of items stored in the heap. + int size() const { return num_items; } + + /// \brief Checks if the heap stores no items. + /// + /// Returns \c true if and only if the heap stores no items. + bool empty() const { return num_items==0; } + + /// \brief Make empty this heap. + /// + /// Make empty this heap. It does not change the cross reference + /// map. If you want to reuse a heap what is not surely empty you + /// should first clear the heap and after that you should set the + /// cross reference map for each item to \c PRE_HEAP. + void clear() { + container.clear(); minimum=0; num_items=0; head=-1; + } + + /// \brief \c item gets to the heap with priority \c value independently + /// if \c item was already there. + /// + /// This method calls \ref push(\c item, \c value) if \c item is not + /// stored in the heap and it calls \ref decrease(\c item, \c value) or + /// \ref increase(\c item, \c value) otherwise. + void set (const Item& item, const Prio& value) { + int i=iimap[item]; + if ( i >= 0 && container[i].in ) { + if ( comp(value, container[i].prio) ) decrease(item, value); + if ( comp(container[i].prio, value) ) increase(item, value); + } else push(item, value); + } + + /// \brief Adds \c item to the heap with priority \c value. + /// + /// Adds \c item to the heap with priority \c value. + /// \pre \c item must not be stored in the heap. + void push (const Item& item, const Prio& value) { + int i=iimap[item]; + if ( i<0 ) { + int s=container.size(); + iimap.set( item,s ); + store st; + st.name=item; + container.push_back(st); + i=s; + } + else { + container[i].parent=container[i].right_neighbor=container[i].child=-1; + container[i].degree=0; + container[i].in=true; + } + container[i].prio=value; + + if( 0==num_items ) { head=i; minimum=i; } + else { merge(i); } + + minimum = find_min(); + + ++num_items; + } + + /// \brief Returns the item with minimum priority relative to \c Compare. + /// + /// This method returns the item with minimum priority relative to \c + /// Compare. + /// \pre The heap must be nonempty. + Item top() const { return container[minimum].name; } + + /// \brief Returns the minimum priority relative to \c Compare. + /// + /// It returns the minimum priority relative to \c Compare. + /// \pre The heap must be nonempty. + const Prio& prio() const { return container[minimum].prio; } + + /// \brief Returns the priority of \c item. + /// + /// It returns the priority of \c item. + /// \pre \c item must be in the heap. + const Prio& operator[](const Item& item) const { + return container[iimap[item]].prio; + } + + /// \brief Deletes the item with minimum priority relative to \c Compare. + /// + /// This method deletes the item with minimum priority relative to \c + /// Compare from the heap. + /// \pre The heap must be non-empty. + void pop() { + container[minimum].in=false; + + int head_child=-1; + if ( container[minimum].child!=-1 ) { + int child=container[minimum].child; + int neighb; + int prev=-1; + while( child!=-1 ) { + neighb=container[child].right_neighbor; + container[child].parent=-1; + container[child].right_neighbor=prev; + head_child=child; + prev=child; + child=neighb; + } + } + + // The first case is that there are only one root. + if ( -1==container[head].right_neighbor ) { + head=head_child; + } + // The case where there are more roots. + else { + if( head!=minimum ) { unlace(minimum); } + else { head=container[head].right_neighbor; } + + merge(head_child); + } + minimum=find_min(); + --num_items; + } + + /// \brief Deletes \c item from the heap. + /// + /// This method deletes \c item from the heap, if \c item was already + /// stored in the heap. It is quite inefficient in Binomial heaps. + void erase (const Item& item) { + int i=iimap[item]; + if ( i >= 0 && container[i].in ) { + decrease( item, container[minimum].prio-1 ); + pop(); + } + } + + /// \brief Decreases the priority of \c item to \c value. + /// + /// This method decreases the priority of \c item to \c value. + /// \pre \c item must be stored in the heap with priority at least \c + /// value relative to \c Compare. + void decrease (Item item, const Prio& value) { + int i=iimap[item]; + + if( comp( value,container[i].prio ) ) { + container[i].prio=value; + + int p_loc=container[i].parent, loc=i; + int parent, child, neighb; + + while( -1!=p_loc && comp(container[loc].prio,container[p_loc].prio) ) { + + // parent set for other loc_child + child=container[loc].child; + while( -1!=child ) { + container[child].parent=p_loc; + child=container[child].right_neighbor; + } + + // parent set for other p_loc_child + child=container[p_loc].child; + while( -1!=child ) { + container[child].parent=loc; + child=container[child].right_neighbor; + } + + child=container[p_loc].child; + container[p_loc].child=container[loc].child; + if( child==loc ) + child=p_loc; + container[loc].child=child; + + // left_neighb set for p_loc + if( container[loc].child!=p_loc ) { + while( container[child].right_neighbor!=loc ) + child=container[child].right_neighbor; + container[child].right_neighbor=p_loc; + } + + // left_neighb set for loc + parent=container[p_loc].parent; + if( -1!=parent ) child=container[parent].child; + else child=head; + + if( child!=p_loc ) { + while( container[child].right_neighbor!=p_loc ) + child=container[child].right_neighbor; + container[child].right_neighbor=loc; + } + + neighb=container[p_loc].right_neighbor; + container[p_loc].right_neighbor=container[loc].right_neighbor; + container[loc].right_neighbor=neighb; + + container[p_loc].parent=loc; + container[loc].parent=parent; + + if( -1!=parent && container[parent].child==p_loc ) + container[parent].child=loc; + + /*if new parent will be the first root*/ + if( head==p_loc ) + head=loc; + + p_loc=container[loc].parent; + } + } + if( comp(value,container[minimum].prio) ) { + minimum=i; + } + } + + /// \brief Increases the priority of \c item to \c value. + /// + /// This method sets the priority of \c item to \c value. Though + /// there is no precondition on the priority of \c item, this + /// method should be used only if it is indeed necessary to increase + /// (relative to \c Compare) the priority of \c item, because this + /// method is inefficient. + void increase (Item item, const Prio& value) { + erase(item); + push(item, value); + } + + + /// \brief Returns if \c item is in, has already been in, or has never + /// been in the heap. + /// + /// This method returns PRE_HEAP if \c item has never been in the + /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP + /// otherwise. In the latter case it is possible that \c item will + /// get back to the heap again. + State state(const Item &item) const { + int i=iimap[item]; + if( i>=0 ) { + if ( container[i].in ) i=0; + else i=-2; + } + return State(i); + } + + /// \brief Sets the state of the \c item in the heap. + /// + /// Sets the state of the \c item in the heap. It can be used to + /// manually clear the heap when it is important to achive the + /// better time complexity. + /// \param i The item. + /// \param st The state. It should not be \c IN_HEAP. + void state(const Item& i, State st) { + switch (st) { + case POST_HEAP: + case PRE_HEAP: + if (state(i) == IN_HEAP) { + erase(i); + } + iimap[i] = st; + break; + case IN_HEAP: + break; + } + } + + private: + int find_min() { + int min_loc=-1, min_val; + int x=head; + if( x!=-1 ) { + min_val=container[x].prio; + min_loc=x; + x=container[x].right_neighbor; + + while( x!=-1 ) { + if( comp( container[x].prio,min_val ) ) { + min_val=container[x].prio; + min_loc=x; + } + x=container[x].right_neighbor; + } + } + return min_loc; + } + + void merge(int a) { + interleave(a); + + int x=head; + if( -1!=x ) { + int x_prev=-1, x_next=container[x].right_neighbor; + while( -1!=x_next ) { + if( container[x].degree!=container[x_next].degree || ( -1!=container[x_next].right_neighbor && container[container[x_next].right_neighbor].degree==container[x].degree ) ) { + x_prev=x; + x=x_next; + } + else { + if( comp(container[x].prio,container[x_next].prio) ) { + container[x].right_neighbor=container[x_next].right_neighbor; + fuse(x_next,x); + } + else { + if( -1==x_prev ) { head=x_next; } + else { + container[x_prev].right_neighbor=x_next; + } + fuse(x,x_next); + x=x_next; + } + } + x_next=container[x].right_neighbor; + } + } + } + + void interleave(int a) { + int other=-1, head_other=-1; + + while( -1!=a || -1!=head ) { + if( -1==a ) { + if( -1==head_other ) { + head_other=head; + } + else { + container[other].right_neighbor=head; + } + head=-1; + } + else if( -1==head ) { + if( -1==head_other ) { + head_other=a; + } + else { + container[other].right_neighbor=a; + } + a=-1; + } + else { + if( container[a].degree