1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/lemon/bin_heap.h Mon May 23 04:48:14 2005 +0000
1.3 @@ -0,0 +1,303 @@
1.4 +/* -*- C++ -*-
1.5 + * lemon/bin_heap.h - Part of LEMON, a generic C++ optimization library
1.6 + *
1.7 + * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
1.8 + * (Egervary Research Group on Combinatorial Optimization, EGRES).
1.9 + *
1.10 + * Permission to use, modify and distribute this software is granted
1.11 + * provided that this copyright notice appears in all copies. For
1.12 + * precise terms see the accompanying LICENSE file.
1.13 + *
1.14 + * This software is provided "AS IS" with no warranty of any kind,
1.15 + * express or implied, and with no claim as to its suitability for any
1.16 + * purpose.
1.17 + *
1.18 + */
1.19 +
1.20 +#ifndef LEMON_BIN_HEAP_H
1.21 +#define LEMON_BIN_HEAP_H
1.22 +
1.23 +///\ingroup auxdat
1.24 +///\file
1.25 +///\brief Binary Heap implementation.
1.26 +
1.27 +#include <vector>
1.28 +#include <utility>
1.29 +#include <functional>
1.30 +
1.31 +namespace lemon {
1.32 +
1.33 + /// \addtogroup auxdat
1.34 + /// @{
1.35 +
1.36 + /// A Binary Heap implementation.
1.37 +
1.38 + ///This class implements the \e binary \e heap data structure. A \e heap
1.39 + ///is a data structure for storing items with specified values called \e
1.40 + ///priorities in such a way that finding the item with minimum priority is
1.41 + ///efficient. \c Compare specifies the ordering of the priorities. In a heap
1.42 + ///one can change the priority of an item, add or erase an item, etc.
1.43 + ///
1.44 + ///\param Item Type of the items to be stored.
1.45 + ///\param Prio Type of the priority of the items.
1.46 + ///\param ItemIntMap A read and writable Item int map, used internally
1.47 + ///to handle the cross references.
1.48 + ///\param Compare A class for the ordering of the priorities. The
1.49 + ///default is \c std::less<Prio>.
1.50 + ///
1.51 + ///\sa FibHeap
1.52 + ///\sa Dijkstra
1.53 + template <typename Item, typename Prio, typename ItemIntMap,
1.54 + typename Compare = std::less<Prio> >
1.55 + class BinHeap {
1.56 +
1.57 + public:
1.58 + typedef Item ItemType;
1.59 + // FIXME: stl-ben nem ezt hivjak value_type -nak, hanem a kovetkezot...
1.60 + typedef Prio PrioType;
1.61 + typedef std::pair<ItemType,PrioType> PairType;
1.62 + typedef ItemIntMap ItemIntMapType;
1.63 + typedef Compare PrioCompare;
1.64 +
1.65 + /// \brief Type to represent the items states.
1.66 + ///
1.67 + /// Each Item element have a state associated to it. It may be "in heap",
1.68 + /// "pre heap" or "post heap". The latter two are indifferent from the
1.69 + /// heap's point of view, but may be useful to the user.
1.70 + ///
1.71 + /// The ItemIntMap \e should be initialized in such way that it maps
1.72 + /// PRE_HEAP (-1) to any element to be put in the heap...
1.73 + enum state_enum {
1.74 + IN_HEAP = 0,
1.75 + PRE_HEAP = -1,
1.76 + POST_HEAP = -2
1.77 + };
1.78 +
1.79 + private:
1.80 + std::vector<PairType> data;
1.81 + Compare comp;
1.82 + ItemIntMap &iim;
1.83 +
1.84 + public:
1.85 + /// \brief The constructor.
1.86 + ///
1.87 + /// The constructor.
1.88 + /// \param _iim should be given to the constructor, since it is used
1.89 + /// internally to handle the cross references. The value of the map
1.90 + /// should be PRE_HEAP (-1) for each element.
1.91 + explicit BinHeap(ItemIntMap &_iim) : iim(_iim) {}
1.92 +
1.93 + /// \brief The constructor.
1.94 + ///
1.95 + /// The constructor.
1.96 + /// \param _iim should be given to the constructor, since it is used
1.97 + /// internally to handle the cross references. The value of the map
1.98 + /// should be PRE_HEAP (-1) for each element.
1.99 + ///
1.100 + /// \param _comp The comparator function object.
1.101 + BinHeap(ItemIntMap &_iim, const Compare &_comp)
1.102 + : iim(_iim), comp(_comp) {}
1.103 +
1.104 +
1.105 + /// The number of items stored in the heap.
1.106 + ///
1.107 + /// \brief Returns the number of items stored in the heap.
1.108 + int size() const { return data.size(); }
1.109 +
1.110 + /// \brief Checks if the heap stores no items.
1.111 + ///
1.112 + /// Returns \c true if and only if the heap stores no items.
1.113 + bool empty() const { return data.empty(); }
1.114 +
1.115 + private:
1.116 + static int parent(int i) { return (i-1)/2; }
1.117 + static int second_child(int i) { return 2*i+2; }
1.118 + bool less(const PairType &p1, const PairType &p2) const {
1.119 + return comp(p1.second, p2.second);
1.120 + }
1.121 +
1.122 + int bubble_up(int hole, PairType p);
1.123 + int bubble_down(int hole, PairType p, int length);
1.124 +
1.125 + void move(const PairType &p, int i) {
1.126 + data[i] = p;
1.127 + iim.set(p.first, i);
1.128 + }
1.129 +
1.130 + void rmidx(int h) {
1.131 + int n = data.size()-1;
1.132 + if( h>=0 && h<=n ) {
1.133 + iim.set(data[h].first, POST_HEAP);
1.134 + if ( h<n ) {
1.135 + bubble_down(h, data[n], n);
1.136 + }
1.137 + data.pop_back();
1.138 + }
1.139 + }
1.140 +
1.141 + public:
1.142 + /// \brief Insert a pair of item and priority into the heap.
1.143 + ///
1.144 + /// Adds \c p.first to the heap with priority \c p.second.
1.145 + /// \param p The pair to insert.
1.146 + void push(const PairType &p) {
1.147 + int n = data.size();
1.148 + data.resize(n+1);
1.149 + bubble_up(n, p);
1.150 + }
1.151 +
1.152 + /// \brief Insert an item into the heap with the given heap.
1.153 + ///
1.154 + /// Adds \c i to the heap with priority \c p.
1.155 + /// \param i The item to insert.
1.156 + /// \param p The priority of the item.
1.157 + void push(const Item &i, const Prio &p) { push(PairType(i,p)); }
1.158 +
1.159 + /// \brief Returns the item with minimum priority relative to \c Compare.
1.160 + ///
1.161 + /// This method returns the item with minimum priority relative to \c
1.162 + /// Compare.
1.163 + /// \pre The heap must be nonempty.
1.164 + Item top() const {
1.165 + return data[0].first;
1.166 + }
1.167 +
1.168 + /// \brief Returns the minimum priority relative to \c Compare.
1.169 + ///
1.170 + /// It returns the minimum priority relative to \c Compare.
1.171 + /// \pre The heap must be nonempty.
1.172 + Prio prio() const {
1.173 + return data[0].second;
1.174 + }
1.175 +
1.176 + /// \brief Deletes the item with minimum priority relative to \c Compare.
1.177 + ///
1.178 + /// This method deletes the item with minimum priority relative to \c
1.179 + /// Compare from the heap.
1.180 + /// \pre The heap must be non-empty.
1.181 + void pop() {
1.182 + rmidx(0);
1.183 + }
1.184 +
1.185 + /// \brief Deletes \c i from the heap.
1.186 + ///
1.187 + /// This method deletes item \c i from the heap, if \c i was
1.188 + /// already stored in the heap.
1.189 + /// \param i The item to erase.
1.190 + void erase(const Item &i) {
1.191 + rmidx(iim[i]);
1.192 + }
1.193 +
1.194 +
1.195 + /// \brief Returns the priority of \c i.
1.196 + ///
1.197 + /// This function returns the priority of item \c i.
1.198 + /// \pre \c i must be in the heap.
1.199 + /// \param i The item.
1.200 + Prio operator[](const Item &i) const {
1.201 + int idx = iim[i];
1.202 + return data[idx].second;
1.203 + }
1.204 +
1.205 + /// \brief \c i gets to the heap with priority \c p independently
1.206 + /// if \c i was already there.
1.207 + ///
1.208 + /// This method calls \ref push(\c i, \c p) if \c i is not stored
1.209 + /// in the heap and sets the priority of \c i to \c p otherwise.
1.210 + /// \param i The item.
1.211 + /// \param p The priority.
1.212 + void set(const Item &i, const Prio &p) {
1.213 + int idx = iim[i];
1.214 + if( idx < 0 ) {
1.215 + push(i,p);
1.216 + }
1.217 + else if( comp(p, data[idx].second) ) {
1.218 + bubble_up(idx, PairType(i,p));
1.219 + }
1.220 + else {
1.221 + bubble_down(idx, PairType(i,p), data.size());
1.222 + }
1.223 + }
1.224 +
1.225 + /// \brief Decreases the priority of \c i to \c p.
1.226 +
1.227 + /// This method decreases the priority of item \c i to \c p.
1.228 + /// \pre \c i must be stored in the heap with priority at least \c
1.229 + /// p relative to \c Compare.
1.230 + /// \param i The item.
1.231 + /// \param p The priority.
1.232 + void decrease(const Item &i, const Prio &p) {
1.233 + int idx = iim[i];
1.234 + bubble_up(idx, PairType(i,p));
1.235 + }
1.236 +
1.237 + /// \brief Increases the priority of \c i to \c p.
1.238 + ///
1.239 + /// This method sets the priority of item \c i to \c p.
1.240 + /// \pre \c i must be stored in the heap with priority at most \c
1.241 + /// p relative to \c Compare.
1.242 + /// \param i The item.
1.243 + /// \param p The priority.
1.244 + void increase(const Item &i, const Prio &p) {
1.245 + int idx = iim[i];
1.246 + bubble_down(idx, PairType(i,p), data.size());
1.247 + }
1.248 +
1.249 + /// \brief Returns if \c item is in, has already been in, or has
1.250 + /// never been in the heap.
1.251 + ///
1.252 + /// This method returns PRE_HEAP if \c item has never been in the
1.253 + /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
1.254 + /// otherwise. In the latter case it is possible that \c item will
1.255 + /// get back to the heap again.
1.256 + /// \param i The item.
1.257 + state_enum state(const Item &i) const {
1.258 + int s = iim[i];
1.259 + if( s>=0 )
1.260 + s=0;
1.261 + return state_enum(s);
1.262 + }
1.263 +
1.264 + }; // class BinHeap
1.265 +
1.266 +
1.267 + template <typename K, typename V, typename M, typename C>
1.268 + int BinHeap<K,V,M,C>::bubble_up(int hole, PairType p) {
1.269 + int par = parent(hole);
1.270 + while( hole>0 && less(p,data[par]) ) {
1.271 + move(data[par],hole);
1.272 + hole = par;
1.273 + par = parent(hole);
1.274 + }
1.275 + move(p, hole);
1.276 + return hole;
1.277 + }
1.278 +
1.279 + template <typename K, typename V, typename M, typename C>
1.280 + int BinHeap<K,V,M,C>::bubble_down(int hole, PairType p, int length) {
1.281 + int child = second_child(hole);
1.282 + while(child < length) {
1.283 + if( less(data[child-1], data[child]) ) {
1.284 + --child;
1.285 + }
1.286 + if( !less(data[child], p) )
1.287 + goto ok;
1.288 + move(data[child], hole);
1.289 + hole = child;
1.290 + child = second_child(hole);
1.291 + }
1.292 + child--;
1.293 + if( child<length && less(data[child], p) ) {
1.294 + move(data[child], hole);
1.295 + hole=child;
1.296 + }
1.297 + ok:
1.298 + move(p, hole);
1.299 + return hole;
1.300 + }
1.301 +
1.302 + ///@}
1.303 +
1.304 +} // namespace lemon
1.305 +
1.306 +#endif // LEMON_BIN_HEAP_H