1.1 --- a/src/lemon/radix_heap.h Sat May 21 21:04:57 2005 +0000
1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
1.3 @@ -1,412 +0,0 @@
1.4 -/* -*- C++ -*-
1.5 - * src/lemon/radix_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_RADIX_HEAP_H
1.21 -#define LEMON_RADIX_HEAP_H
1.22 -
1.23 -///\ingroup auxdat
1.24 -///\file
1.25 -///\brief Radix Heap implementation.
1.26 -
1.27 -#include <vector>
1.28 -#include <lemon/error.h>
1.29 -
1.30 -namespace lemon {
1.31 -
1.32 - /// \addtogroup auxdat
1.33 - /// @{
1.34 -
1.35 - /// \brief Exception thrown by RadixHeap.
1.36 - ///
1.37 - /// This Exception is thrown when a smaller priority
1.38 - /// is inserted into the \e RadixHeap then the last time erased.
1.39 - /// \see RadixHeap
1.40 - /// \author Balazs Dezso
1.41 -
1.42 - class UnderFlowPriorityError : public RuntimeError {
1.43 - public:
1.44 - virtual const char* exceptionName() const {
1.45 - return "lemon::UnderFlowPriorityError";
1.46 - }
1.47 - };
1.48 -
1.49 - /// \brief A Radix Heap implementation.
1.50 - ///
1.51 - /// This class implements the \e radix \e heap data structure. A \e heap
1.52 - /// is a data structure for storing items with specified values called \e
1.53 - /// priorities in such a way that finding the item with minimum priority is
1.54 - /// efficient. This heap type can store only items with \e int priority.
1.55 - /// In a heap one can change the priority of an item, add or erase an
1.56 - /// item, but the priority cannot be decreased under the last removed
1.57 - /// item's priority.
1.58 - ///
1.59 - /// \param _Item Type of the items to be stored.
1.60 - /// \param _ItemIntMap A read and writable Item int map, used internally
1.61 - /// to handle the cross references.
1.62 - ///
1.63 - /// \see BinHeap
1.64 - /// \see Dijkstra
1.65 - /// \author Balazs Dezso
1.66 -
1.67 - template <typename _Item, typename _ItemIntMap>
1.68 - class RadixHeap {
1.69 -
1.70 - public:
1.71 - typedef _Item Item;
1.72 - typedef int Prio;
1.73 - typedef _ItemIntMap ItemIntMap;
1.74 -
1.75 - /// \brief Type to represent the items states.
1.76 - ///
1.77 - /// Each Item element have a state associated to it. It may be "in heap",
1.78 - /// "pre heap" or "post heap". The latter two are indifferent from the
1.79 - /// heap's point of view, but may be useful to the user.
1.80 - ///
1.81 - /// The ItemIntMap \e should be initialized in such way that it maps
1.82 - /// PRE_HEAP (-1) to any element to be put in the heap...
1.83 - enum state_enum {
1.84 - IN_HEAP = 0,
1.85 - PRE_HEAP = -1,
1.86 - POST_HEAP = -2
1.87 - };
1.88 -
1.89 - private:
1.90 -
1.91 - struct RadixItem {
1.92 - int prev, next, box;
1.93 - Item item;
1.94 - int prio;
1.95 - RadixItem(Item _item, int _prio) : item(_item), prio(_prio) {}
1.96 - };
1.97 -
1.98 - struct RadixBox {
1.99 - int first;
1.100 - int min, size;
1.101 - RadixBox(int _min, int _size) : first(-1), min(_min), size(_size) {}
1.102 - };
1.103 -
1.104 - std::vector<RadixItem> data;
1.105 - std::vector<RadixBox> boxes;
1.106 -
1.107 - ItemIntMap &iim;
1.108 -
1.109 -
1.110 - public:
1.111 - /// \brief The constructor.
1.112 - ///
1.113 - /// The constructor.
1.114 - /// \param _iim should be given to the constructor, since it is used
1.115 - /// internally to handle the cross references. The value of the map
1.116 - /// should be PRE_HEAP (-1) for each element.
1.117 - explicit RadixHeap(ItemIntMap &_iim) : iim(_iim) {
1.118 - boxes.push_back(RadixBox(0, 1));
1.119 - boxes.push_back(RadixBox(1, 1));
1.120 - }
1.121 -
1.122 - /// \brief The constructor.
1.123 - ///
1.124 - /// The constructor.
1.125 - ///
1.126 - /// \param _iim It should be given to the constructor, since it is used
1.127 - /// internally to handle the cross references. The value of the map
1.128 - /// should be PRE_HEAP (-1) for each element.
1.129 - ///
1.130 - /// \param capacity It determines the initial capacity of the heap.
1.131 - RadixHeap(ItemIntMap &_iim, int capacity) : iim(_iim) {
1.132 - boxes.push_back(RadixBox(0, 1));
1.133 - boxes.push_back(RadixBox(1, 1));
1.134 - while (upper(boxes.back(), capacity)) {
1.135 - extend();
1.136 - }
1.137 - }
1.138 -
1.139 - /// The number of items stored in the heap.
1.140 - ///
1.141 - /// \brief Returns the number of items stored in the heap.
1.142 - int size() const { return data.size(); }
1.143 - /// \brief Checks if the heap stores no items.
1.144 - ///
1.145 - /// Returns \c true if and only if the heap stores no items.
1.146 - bool empty() const { return data.empty(); }
1.147 -
1.148 - private:
1.149 -
1.150 - bool upper(int box, Prio prio) {
1.151 - return prio < boxes[box].min;
1.152 - }
1.153 -
1.154 - bool lower(int box, Prio prio) {
1.155 - return prio >= boxes[box].min + boxes[box].size;
1.156 - }
1.157 -
1.158 - /// \brief Remove item from the box list.
1.159 - void remove(int index) {
1.160 - if (data[index].prev >= 0) {
1.161 - data[data[index].prev].next = data[index].next;
1.162 - } else {
1.163 - boxes[data[index].box].first = data[index].next;
1.164 - }
1.165 - if (data[index].next >= 0) {
1.166 - data[data[index].next].prev = data[index].prev;
1.167 - }
1.168 - }
1.169 -
1.170 - /// \brief Insert item into the box list.
1.171 - void insert(int box, int index) {
1.172 - if (boxes[box].first == -1) {
1.173 - boxes[box].first = index;
1.174 - data[index].next = data[index].prev = -1;
1.175 - } else {
1.176 - data[index].next = boxes[box].first;
1.177 - data[boxes[box].first].prev = index;
1.178 - data[index].prev = -1;
1.179 - boxes[box].first = index;
1.180 - }
1.181 - data[index].box = box;
1.182 - }
1.183 -
1.184 - /// \brief Add a new box to the box list.
1.185 - void extend() {
1.186 - int min = boxes.back().min + boxes.back().size;
1.187 - int size = 2 * boxes.back().size;
1.188 - boxes.push_back(RadixBox(min, size));
1.189 - }
1.190 -
1.191 - /// \brief Move an item up into the proper box.
1.192 - void bubble_up(int index) {
1.193 - if (!lower(data[index].box, data[index].prio)) return;
1.194 - remove(index);
1.195 - int box = findUp(data[index].box, data[index].prio);
1.196 - insert(box, index);
1.197 - }
1.198 -
1.199 - /// \brief Find up the proper box for the item with the given prio.
1.200 - int findUp(int start, int prio) {
1.201 - while (lower(start, prio)) {
1.202 - if (++start == (int)boxes.size()) {
1.203 - extend();
1.204 - }
1.205 - }
1.206 - return start;
1.207 - }
1.208 -
1.209 - /// \brief Move an item down into the proper box.
1.210 - void bubble_down(int index) {
1.211 - if (!upper(data[index].box, data[index].prio)) return;
1.212 - remove(index);
1.213 - int box = findDown(data[index].box, data[index].prio);
1.214 - insert(box, index);
1.215 - }
1.216 -
1.217 - /// \brief Find up the proper box for the item with the given prio.
1.218 - int findDown(int start, int prio) {
1.219 - while (upper(start, prio)) {
1.220 - if (--start < 0) throw UnderFlowPriorityError();
1.221 - }
1.222 - return start;
1.223 - }
1.224 -
1.225 - /// \brief Find the first not empty box.
1.226 - int findFirst() {
1.227 - int first = 0;
1.228 - while (boxes[first].first == -1) ++first;
1.229 - return first;
1.230 - }
1.231 -
1.232 - /// \brief Gives back the minimal prio of the box.
1.233 - int minValue(int box) {
1.234 - int min = data[boxes[box].first].prio;
1.235 - for (int k = boxes[box].first; k != -1; k = data[k].next) {
1.236 - if (data[k].prio < min) min = data[k].prio;
1.237 - }
1.238 - return min;
1.239 - }
1.240 -
1.241 - /// \brief Rearrange the items of the heap and makes the
1.242 - /// first box not empty.
1.243 - void moveDown() {
1.244 - int box = findFirst();
1.245 - if (box == 0) return;
1.246 - int min = minValue(box);
1.247 - for (int i = 0; i <= box; ++i) {
1.248 - boxes[i].min = min;
1.249 - min += boxes[i].size;
1.250 - }
1.251 - int curr = boxes[box].first, next;
1.252 - while (curr != -1) {
1.253 - next = data[curr].next;
1.254 - bubble_down(curr);
1.255 - curr = next;
1.256 - }
1.257 - }
1.258 -
1.259 - void relocate_last(int index) {
1.260 - if (index != (int)data.size() - 1) {
1.261 - data[index] = data.back();
1.262 - if (data[index].prev != -1) {
1.263 - data[data[index].prev].next = index;
1.264 - } else {
1.265 - boxes[data[index].box].first = index;
1.266 - }
1.267 - if (data[index].next != -1) {
1.268 - data[data[index].next].prev = index;
1.269 - }
1.270 - iim[data[index].item] = index;
1.271 - }
1.272 - data.pop_back();
1.273 - }
1.274 -
1.275 - public:
1.276 -
1.277 - /// \brief Insert an item into the heap with the given heap.
1.278 - ///
1.279 - /// Adds \c i to the heap with priority \c p.
1.280 - /// \param i The item to insert.
1.281 - /// \param p The priority of the item.
1.282 - void push(const Item &i, const Prio &p) {
1.283 - int n = data.size();
1.284 - iim.set(i, n);
1.285 - data.push_back(RadixItem(i, p));
1.286 - while (lower(boxes.size() - 1, p)) {
1.287 - extend();
1.288 - }
1.289 - int box = findDown(boxes.size() - 1, p);
1.290 - insert(box, n);
1.291 - }
1.292 -
1.293 - /// \brief Returns the item with minimum priority.
1.294 - ///
1.295 - /// This method returns the item with minimum priority.
1.296 - /// \pre The heap must be nonempty.
1.297 - Item top() const {
1.298 - const_cast<RadixHeap<Item, ItemIntMap>*>(this)->moveDown();
1.299 - return data[boxes[0].first].item;
1.300 - }
1.301 -
1.302 - /// \brief Returns the minimum priority.
1.303 - ///
1.304 - /// It returns the minimum priority.
1.305 - /// \pre The heap must be nonempty.
1.306 - Prio prio() const {
1.307 - const_cast<RadixHeap<Item, ItemIntMap>*>(this)->moveDown();
1.308 - return data[boxes[0].first].prio;
1.309 - }
1.310 -
1.311 - /// \brief Deletes the item with minimum priority.
1.312 - ///
1.313 - /// This method deletes the item with minimum priority.
1.314 - /// \pre The heap must be non-empty.
1.315 - void pop() {
1.316 - moveDown();
1.317 - int index = boxes[0].first;
1.318 - iim[data[index].item] = POST_HEAP;
1.319 - remove(index);
1.320 - relocate_last(index);
1.321 - }
1.322 -
1.323 - /// \brief Deletes \c i from the heap.
1.324 - ///
1.325 - /// This method deletes item \c i from the heap, if \c i was
1.326 - /// already stored in the heap.
1.327 - /// \param i The item to erase.
1.328 - void erase(const Item &i) {
1.329 - int index = iim[i];
1.330 - iim[i] = POST_HEAP;
1.331 - remove(index);
1.332 - relocate_last(index);
1.333 - }
1.334 -
1.335 - /// \brief Returns the priority of \c i.
1.336 - ///
1.337 - /// This function returns the priority of item \c i.
1.338 - /// \pre \c i must be in the heap.
1.339 - /// \param i The item.
1.340 - Prio operator[](const Item &i) const {
1.341 - int idx = iim[i];
1.342 - return data[idx].prio;
1.343 - }
1.344 -
1.345 - /// \brief \c i gets to the heap with priority \c p independently
1.346 - /// if \c i was already there.
1.347 - ///
1.348 - /// This method calls \ref push(\c i, \c p) if \c i is not stored
1.349 - /// in the heap and sets the priority of \c i to \c p otherwise.
1.350 - /// It may throw an \e UnderFlowPriorityException.
1.351 - /// \param i The item.
1.352 - /// \param p The priority.
1.353 - void set(const Item &i, const Prio &p) {
1.354 - int idx = iim[i];
1.355 - if( idx < 0 ) {
1.356 - push(i, p);
1.357 - }
1.358 - else if( p >= data[idx].prio ) {
1.359 - data[idx].prio = p;
1.360 - bubble_up(idx);
1.361 - } else {
1.362 - data[idx].prio = p;
1.363 - bubble_down(idx);
1.364 - }
1.365 - }
1.366 -
1.367 -
1.368 - /// \brief Decreases the priority of \c i to \c p.
1.369 - ///
1.370 - /// This method decreases the priority of item \c i to \c p.
1.371 - /// \pre \c i must be stored in the heap with priority at least \c p, and
1.372 - /// \c should be greater then the last removed item's priority.
1.373 - /// \param i The item.
1.374 - /// \param p The priority.
1.375 - void decrease(const Item &i, const Prio &p) {
1.376 - int idx = iim[i];
1.377 - data[idx].prio = p;
1.378 - bubble_down(idx);
1.379 - }
1.380 -
1.381 - /// \brief Increases the priority of \c i to \c p.
1.382 - ///
1.383 - /// This method sets the priority of item \c i to \c p.
1.384 - /// \pre \c i must be stored in the heap with priority at most \c
1.385 - /// p relative to \c Compare.
1.386 - /// \param i The item.
1.387 - /// \param p The priority.
1.388 - void increase(const Item &i, const Prio &p) {
1.389 - int idx = iim[i];
1.390 - data[idx].prio = p;
1.391 - bubble_up(idx);
1.392 - }
1.393 -
1.394 - /// \brief Returns if \c item is in, has already been in, or has
1.395 - /// never been in the heap.
1.396 - ///
1.397 - /// This method returns PRE_HEAP if \c item has never been in the
1.398 - /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
1.399 - /// otherwise. In the latter case it is possible that \c item will
1.400 - /// get back to the heap again.
1.401 - /// \param i The item.
1.402 - state_enum state(const Item &i) const {
1.403 - int s = iim[i];
1.404 - if( s >= 0 ) s = 0;
1.405 - return state_enum(s);
1.406 - }
1.407 -
1.408 - }; // class RadixHeap
1.409 -
1.410 -
1.411 - ///@}
1.412 -
1.413 -} // namespace lemon
1.414 -
1.415 -#endif // LEMON_RADIX_HEAP_H