1.1 --- a/lemon/fourary_heap.h Tue Mar 02 10:27:47 2010 +0100
1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
1.3 @@ -1,342 +0,0 @@
1.4 -/* -*- mode: C++; indent-tabs-mode: nil; -*-
1.5 - *
1.6 - * This file is a part of LEMON, a generic C++ optimization library.
1.7 - *
1.8 - * Copyright (C) 2003-2009
1.9 - * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
1.10 - * (Egervary Research Group on Combinatorial Optimization, EGRES).
1.11 - *
1.12 - * Permission to use, modify and distribute this software is granted
1.13 - * provided that this copyright notice appears in all copies. For
1.14 - * precise terms see the accompanying LICENSE file.
1.15 - *
1.16 - * This software is provided "AS IS" with no warranty of any kind,
1.17 - * express or implied, and with no claim as to its suitability for any
1.18 - * purpose.
1.19 - *
1.20 - */
1.21 -
1.22 -#ifndef LEMON_FOURARY_HEAP_H
1.23 -#define LEMON_FOURARY_HEAP_H
1.24 -
1.25 -///\ingroup heaps
1.26 -///\file
1.27 -///\brief Fourary heap implementation.
1.28 -
1.29 -#include <vector>
1.30 -#include <utility>
1.31 -#include <functional>
1.32 -
1.33 -namespace lemon {
1.34 -
1.35 - /// \ingroup heaps
1.36 - ///
1.37 - ///\brief Fourary heap data structure.
1.38 - ///
1.39 - /// This class implements the \e fourary \e heap data structure.
1.40 - /// It fully conforms to the \ref concepts::Heap "heap concept".
1.41 - ///
1.42 - /// The fourary heap is a specialization of the \ref KaryHeap "K-ary heap"
1.43 - /// for <tt>K=4</tt>. It is similar to the \ref BinHeap "binary heap",
1.44 - /// but its nodes have at most four children, instead of two.
1.45 - ///
1.46 - /// \tparam PR Type of the priorities of the items.
1.47 - /// \tparam IM A read-writable item map with \c int values, used
1.48 - /// internally to handle the cross references.
1.49 - /// \tparam CMP A functor class for comparing the priorities.
1.50 - /// The default is \c std::less<PR>.
1.51 - ///
1.52 - ///\sa BinHeap
1.53 - ///\sa KaryHeap
1.54 -#ifdef DOXYGEN
1.55 - template <typename PR, typename IM, typename CMP>
1.56 -#else
1.57 - template <typename PR, typename IM, typename CMP = std::less<PR> >
1.58 -#endif
1.59 - class FouraryHeap {
1.60 - public:
1.61 - /// Type of the item-int map.
1.62 - typedef IM ItemIntMap;
1.63 - /// Type of the priorities.
1.64 - typedef PR Prio;
1.65 - /// Type of the items stored in the heap.
1.66 - typedef typename ItemIntMap::Key Item;
1.67 - /// Type of the item-priority pairs.
1.68 - typedef std::pair<Item,Prio> Pair;
1.69 - /// Functor type for comparing the priorities.
1.70 - typedef CMP Compare;
1.71 -
1.72 - /// \brief Type to represent the states of the items.
1.73 - ///
1.74 - /// Each item has a state associated to it. It can be "in heap",
1.75 - /// "pre-heap" or "post-heap". The latter two are indifferent from the
1.76 - /// heap's point of view, but may be useful to the user.
1.77 - ///
1.78 - /// The item-int map must be initialized in such way that it assigns
1.79 - /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
1.80 - enum State {
1.81 - IN_HEAP = 0, ///< = 0.
1.82 - PRE_HEAP = -1, ///< = -1.
1.83 - POST_HEAP = -2 ///< = -2.
1.84 - };
1.85 -
1.86 - private:
1.87 - std::vector<Pair> _data;
1.88 - Compare _comp;
1.89 - ItemIntMap &_iim;
1.90 -
1.91 - public:
1.92 - /// \brief Constructor.
1.93 - ///
1.94 - /// Constructor.
1.95 - /// \param map A map that assigns \c int values to the items.
1.96 - /// It is used internally to handle the cross references.
1.97 - /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
1.98 - explicit FouraryHeap(ItemIntMap &map) : _iim(map) {}
1.99 -
1.100 - /// \brief Constructor.
1.101 - ///
1.102 - /// Constructor.
1.103 - /// \param map A map that assigns \c int values to the items.
1.104 - /// It is used internally to handle the cross references.
1.105 - /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
1.106 - /// \param comp The function object used for comparing the priorities.
1.107 - FouraryHeap(ItemIntMap &map, const Compare &comp)
1.108 - : _iim(map), _comp(comp) {}
1.109 -
1.110 - /// \brief The number of items stored in the heap.
1.111 - ///
1.112 - /// This function returns the number of items stored in the heap.
1.113 - int size() const { return _data.size(); }
1.114 -
1.115 - /// \brief Check if the heap is empty.
1.116 - ///
1.117 - /// This function returns \c true if the heap is empty.
1.118 - bool empty() const { return _data.empty(); }
1.119 -
1.120 - /// \brief Make the heap empty.
1.121 - ///
1.122 - /// This functon makes the heap empty.
1.123 - /// It does not change the cross reference map. If you want to reuse
1.124 - /// a heap that is not surely empty, you should first clear it and
1.125 - /// then you should set the cross reference map to \c PRE_HEAP
1.126 - /// for each item.
1.127 - void clear() { _data.clear(); }
1.128 -
1.129 - private:
1.130 - static int parent(int i) { return (i-1)/4; }
1.131 - static int firstChild(int i) { return 4*i+1; }
1.132 -
1.133 - bool less(const Pair &p1, const Pair &p2) const {
1.134 - return _comp(p1.second, p2.second);
1.135 - }
1.136 -
1.137 - void bubbleUp(int hole, Pair p) {
1.138 - int par = parent(hole);
1.139 - while( hole>0 && less(p,_data[par]) ) {
1.140 - move(_data[par],hole);
1.141 - hole = par;
1.142 - par = parent(hole);
1.143 - }
1.144 - move(p, hole);
1.145 - }
1.146 -
1.147 - void bubbleDown(int hole, Pair p, int length) {
1.148 - if( length>1 ) {
1.149 - int child = firstChild(hole);
1.150 - while( child+3<length ) {
1.151 - int min=child;
1.152 - if( less(_data[++child], _data[min]) ) min=child;
1.153 - if( less(_data[++child], _data[min]) ) min=child;
1.154 - if( less(_data[++child], _data[min]) ) min=child;
1.155 - if( !less(_data[min], p) )
1.156 - goto ok;
1.157 - move(_data[min], hole);
1.158 - hole = min;
1.159 - child = firstChild(hole);
1.160 - }
1.161 - if ( child<length ) {
1.162 - int min = child;
1.163 - if( ++child<length && less(_data[child], _data[min]) ) min=child;
1.164 - if( ++child<length && less(_data[child], _data[min]) ) min=child;
1.165 - if( less(_data[min], p) ) {
1.166 - move(_data[min], hole);
1.167 - hole = min;
1.168 - }
1.169 - }
1.170 - }
1.171 - ok:
1.172 - move(p, hole);
1.173 - }
1.174 -
1.175 - void move(const Pair &p, int i) {
1.176 - _data[i] = p;
1.177 - _iim.set(p.first, i);
1.178 - }
1.179 -
1.180 - public:
1.181 - /// \brief Insert a pair of item and priority into the heap.
1.182 - ///
1.183 - /// This function inserts \c p.first to the heap with priority
1.184 - /// \c p.second.
1.185 - /// \param p The pair to insert.
1.186 - /// \pre \c p.first must not be stored in the heap.
1.187 - void push(const Pair &p) {
1.188 - int n = _data.size();
1.189 - _data.resize(n+1);
1.190 - bubbleUp(n, p);
1.191 - }
1.192 -
1.193 - /// \brief Insert an item into the heap with the given priority.
1.194 - ///
1.195 - /// This function inserts the given item into the heap with the
1.196 - /// given priority.
1.197 - /// \param i The item to insert.
1.198 - /// \param p The priority of the item.
1.199 - /// \pre \e i must not be stored in the heap.
1.200 - void push(const Item &i, const Prio &p) { push(Pair(i,p)); }
1.201 -
1.202 - /// \brief Return the item having minimum priority.
1.203 - ///
1.204 - /// This function returns the item having minimum priority.
1.205 - /// \pre The heap must be non-empty.
1.206 - Item top() const { return _data[0].first; }
1.207 -
1.208 - /// \brief The minimum priority.
1.209 - ///
1.210 - /// This function returns the minimum priority.
1.211 - /// \pre The heap must be non-empty.
1.212 - Prio prio() const { return _data[0].second; }
1.213 -
1.214 - /// \brief Remove the item having minimum priority.
1.215 - ///
1.216 - /// This function removes the item having minimum priority.
1.217 - /// \pre The heap must be non-empty.
1.218 - void pop() {
1.219 - int n = _data.size()-1;
1.220 - _iim.set(_data[0].first, POST_HEAP);
1.221 - if (n>0) bubbleDown(0, _data[n], n);
1.222 - _data.pop_back();
1.223 - }
1.224 -
1.225 - /// \brief Remove the given item from the heap.
1.226 - ///
1.227 - /// This function removes the given item from the heap if it is
1.228 - /// already stored.
1.229 - /// \param i The item to delete.
1.230 - /// \pre \e i must be in the heap.
1.231 - void erase(const Item &i) {
1.232 - int h = _iim[i];
1.233 - int n = _data.size()-1;
1.234 - _iim.set(_data[h].first, POST_HEAP);
1.235 - if( h<n ) {
1.236 - if( less(_data[parent(h)], _data[n]) )
1.237 - bubbleDown(h, _data[n], n);
1.238 - else
1.239 - bubbleUp(h, _data[n]);
1.240 - }
1.241 - _data.pop_back();
1.242 - }
1.243 -
1.244 - /// \brief The priority of the given item.
1.245 - ///
1.246 - /// This function returns the priority of the given item.
1.247 - /// \param i The item.
1.248 - /// \pre \e i must be in the heap.
1.249 - Prio operator[](const Item &i) const {
1.250 - int idx = _iim[i];
1.251 - return _data[idx].second;
1.252 - }
1.253 -
1.254 - /// \brief Set the priority of an item or insert it, if it is
1.255 - /// not stored in the heap.
1.256 - ///
1.257 - /// This method sets the priority of the given item if it is
1.258 - /// already stored in the heap. Otherwise it inserts the given
1.259 - /// item into the heap with the given priority.
1.260 - /// \param i The item.
1.261 - /// \param p The priority.
1.262 - void set(const Item &i, const Prio &p) {
1.263 - int idx = _iim[i];
1.264 - if( idx < 0 )
1.265 - push(i,p);
1.266 - else if( _comp(p, _data[idx].second) )
1.267 - bubbleUp(idx, Pair(i,p));
1.268 - else
1.269 - bubbleDown(idx, Pair(i,p), _data.size());
1.270 - }
1.271 -
1.272 - /// \brief Decrease the priority of an item to the given value.
1.273 - ///
1.274 - /// This function decreases the priority of an item to the given value.
1.275 - /// \param i The item.
1.276 - /// \param p The priority.
1.277 - /// \pre \e i must be stored in the heap with priority at least \e p.
1.278 - void decrease(const Item &i, const Prio &p) {
1.279 - int idx = _iim[i];
1.280 - bubbleUp(idx, Pair(i,p));
1.281 - }
1.282 -
1.283 - /// \brief Increase the priority of an item to the given value.
1.284 - ///
1.285 - /// This function increases the priority of an item to the given value.
1.286 - /// \param i The item.
1.287 - /// \param p The priority.
1.288 - /// \pre \e i must be stored in the heap with priority at most \e p.
1.289 - void increase(const Item &i, const Prio &p) {
1.290 - int idx = _iim[i];
1.291 - bubbleDown(idx, Pair(i,p), _data.size());
1.292 - }
1.293 -
1.294 - /// \brief Return the state of an item.
1.295 - ///
1.296 - /// This method returns \c PRE_HEAP if the given item has never
1.297 - /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
1.298 - /// and \c POST_HEAP otherwise.
1.299 - /// In the latter case it is possible that the item will get back
1.300 - /// to the heap again.
1.301 - /// \param i The item.
1.302 - State state(const Item &i) const {
1.303 - int s = _iim[i];
1.304 - if (s>=0) s=0;
1.305 - return State(s);
1.306 - }
1.307 -
1.308 - /// \brief Set the state of an item in the heap.
1.309 - ///
1.310 - /// This function sets the state of the given item in the heap.
1.311 - /// It can be used to manually clear the heap when it is important
1.312 - /// to achive better time complexity.
1.313 - /// \param i The item.
1.314 - /// \param st The state. It should not be \c IN_HEAP.
1.315 - void state(const Item& i, State st) {
1.316 - switch (st) {
1.317 - case POST_HEAP:
1.318 - case PRE_HEAP:
1.319 - if (state(i) == IN_HEAP) erase(i);
1.320 - _iim[i] = st;
1.321 - break;
1.322 - case IN_HEAP:
1.323 - break;
1.324 - }
1.325 - }
1.326 -
1.327 - /// \brief Replace an item in the heap.
1.328 - ///
1.329 - /// This function replaces item \c i with item \c j.
1.330 - /// Item \c i must be in the heap, while \c j must be out of the heap.
1.331 - /// After calling this method, item \c i will be out of the
1.332 - /// heap and \c j will be in the heap with the same prioriority
1.333 - /// as item \c i had before.
1.334 - void replace(const Item& i, const Item& j) {
1.335 - int idx = _iim[i];
1.336 - _iim.set(i, _iim[j]);
1.337 - _iim.set(j, idx);
1.338 - _data[idx].first = j;
1.339 - }
1.340 -
1.341 - }; // class FouraryHeap
1.342 -
1.343 -} // namespace lemon
1.344 -
1.345 -#endif // LEMON_FOURARY_HEAP_H