1.1 --- a/src/lemon/bin_heap.h Sat May 21 21:04:57 2005 +0000
1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
1.3 @@ -1,303 +0,0 @@
1.4 -/* -*- C++ -*-
1.5 - * src/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