1.1 --- a/lemon/radix_heap.h Sun Feb 21 18:55:01 2010 +0100
1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
1.3 @@ -1,433 +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_RADIX_HEAP_H
1.23 -#define LEMON_RADIX_HEAP_H
1.24 -
1.25 -///\ingroup auxdat
1.26 -///\file
1.27 -///\brief Radix Heap implementation.
1.28 -
1.29 -#include <vector>
1.30 -#include <lemon/error.h>
1.31 -
1.32 -namespace lemon {
1.33 -
1.34 -
1.35 - /// \ingroup auxdata
1.36 - ///
1.37 - /// \brief A Radix Heap implementation.
1.38 - ///
1.39 - /// This class implements the \e radix \e heap data structure. A \e heap
1.40 - /// is a data structure for storing items with specified values called \e
1.41 - /// priorities in such a way that finding the item with minimum priority is
1.42 - /// efficient. This heap type can store only items with \e int priority.
1.43 - /// In a heap one can change the priority of an item, add or erase an
1.44 - /// item, but the priority cannot be decreased under the last removed
1.45 - /// item's priority.
1.46 - ///
1.47 - /// \param IM A read and writable Item int map, used internally
1.48 - /// to handle the cross references.
1.49 - ///
1.50 - /// \see BinHeap
1.51 - /// \see Dijkstra
1.52 - template <typename IM>
1.53 - class RadixHeap {
1.54 -
1.55 - public:
1.56 - typedef typename IM::Key Item;
1.57 - typedef int Prio;
1.58 - typedef IM ItemIntMap;
1.59 -
1.60 - /// \brief Exception thrown by RadixHeap.
1.61 - ///
1.62 - /// This Exception is thrown when a smaller priority
1.63 - /// is inserted into the \e RadixHeap then the last time erased.
1.64 - /// \see RadixHeap
1.65 -
1.66 - class UnderFlowPriorityError : public Exception {
1.67 - public:
1.68 - virtual const char* what() const throw() {
1.69 - return "lemon::RadixHeap::UnderFlowPriorityError";
1.70 - }
1.71 - };
1.72 -
1.73 - /// \brief Type to represent the items states.
1.74 - ///
1.75 - /// Each Item element have a state associated to it. It may be "in heap",
1.76 - /// "pre heap" or "post heap". The latter two are indifferent from the
1.77 - /// heap's point of view, but may be useful to the user.
1.78 - ///
1.79 - /// The ItemIntMap \e should be initialized in such way that it maps
1.80 - /// PRE_HEAP (-1) to any element to be put in the heap...
1.81 - enum State {
1.82 - IN_HEAP = 0,
1.83 - PRE_HEAP = -1,
1.84 - POST_HEAP = -2
1.85 - };
1.86 -
1.87 - private:
1.88 -
1.89 - struct RadixItem {
1.90 - int prev, next, box;
1.91 - Item item;
1.92 - int prio;
1.93 - RadixItem(Item _item, int _prio) : item(_item), prio(_prio) {}
1.94 - };
1.95 -
1.96 - struct RadixBox {
1.97 - int first;
1.98 - int min, size;
1.99 - RadixBox(int _min, int _size) : first(-1), min(_min), size(_size) {}
1.100 - };
1.101 -
1.102 - std::vector<RadixItem> data;
1.103 - std::vector<RadixBox> boxes;
1.104 -
1.105 - ItemIntMap &_iim;
1.106 -
1.107 -
1.108 - public:
1.109 - /// \brief The constructor.
1.110 - ///
1.111 - /// The constructor.
1.112 - ///
1.113 - /// \param map It should be given to the constructor, since it is used
1.114 - /// internally to handle the cross references. The value of the map
1.115 - /// should be PRE_HEAP (-1) for each element.
1.116 - ///
1.117 - /// \param minimal The initial minimal value of the heap.
1.118 - /// \param capacity It determines the initial capacity of the heap.
1.119 - RadixHeap(ItemIntMap &map, int minimal = 0, int capacity = 0)
1.120 - : _iim(map) {
1.121 - boxes.push_back(RadixBox(minimal, 1));
1.122 - boxes.push_back(RadixBox(minimal + 1, 1));
1.123 - while (lower(boxes.size() - 1, capacity + minimal - 1)) {
1.124 - extend();
1.125 - }
1.126 - }
1.127 -
1.128 - /// The number of items stored in the heap.
1.129 - ///
1.130 - /// \brief Returns the number of items stored in the heap.
1.131 - int size() const { return data.size(); }
1.132 - /// \brief Checks if the heap stores no items.
1.133 - ///
1.134 - /// Returns \c true if and only if the heap stores no items.
1.135 - bool empty() const { return data.empty(); }
1.136 -
1.137 - /// \brief Make empty this heap.
1.138 - ///
1.139 - /// Make empty this heap. It does not change the cross reference
1.140 - /// map. If you want to reuse a heap what is not surely empty you
1.141 - /// should first clear the heap and after that you should set the
1.142 - /// cross reference map for each item to \c PRE_HEAP.
1.143 - void clear(int minimal = 0, int capacity = 0) {
1.144 - data.clear(); boxes.clear();
1.145 - boxes.push_back(RadixBox(minimal, 1));
1.146 - boxes.push_back(RadixBox(minimal + 1, 1));
1.147 - while (lower(boxes.size() - 1, capacity + minimal - 1)) {
1.148 - extend();
1.149 - }
1.150 - }
1.151 -
1.152 - private:
1.153 -
1.154 - bool upper(int box, Prio pr) {
1.155 - return pr < boxes[box].min;
1.156 - }
1.157 -
1.158 - bool lower(int box, Prio pr) {
1.159 - return pr >= boxes[box].min + boxes[box].size;
1.160 - }
1.161 -
1.162 - /// \brief Remove item from the box list.
1.163 - void remove(int index) {
1.164 - if (data[index].prev >= 0) {
1.165 - data[data[index].prev].next = data[index].next;
1.166 - } else {
1.167 - boxes[data[index].box].first = data[index].next;
1.168 - }
1.169 - if (data[index].next >= 0) {
1.170 - data[data[index].next].prev = data[index].prev;
1.171 - }
1.172 - }
1.173 -
1.174 - /// \brief Insert item into the box list.
1.175 - void insert(int box, int index) {
1.176 - if (boxes[box].first == -1) {
1.177 - boxes[box].first = index;
1.178 - data[index].next = data[index].prev = -1;
1.179 - } else {
1.180 - data[index].next = boxes[box].first;
1.181 - data[boxes[box].first].prev = index;
1.182 - data[index].prev = -1;
1.183 - boxes[box].first = index;
1.184 - }
1.185 - data[index].box = box;
1.186 - }
1.187 -
1.188 - /// \brief Add a new box to the box list.
1.189 - void extend() {
1.190 - int min = boxes.back().min + boxes.back().size;
1.191 - int bs = 2 * boxes.back().size;
1.192 - boxes.push_back(RadixBox(min, bs));
1.193 - }
1.194 -
1.195 - /// \brief Move an item up into the proper box.
1.196 - void bubble_up(int index) {
1.197 - if (!lower(data[index].box, data[index].prio)) return;
1.198 - remove(index);
1.199 - int box = findUp(data[index].box, data[index].prio);
1.200 - insert(box, index);
1.201 - }
1.202 -
1.203 - /// \brief Find up the proper box for the item with the given prio.
1.204 - int findUp(int start, int pr) {
1.205 - while (lower(start, pr)) {
1.206 - if (++start == int(boxes.size())) {
1.207 - extend();
1.208 - }
1.209 - }
1.210 - return start;
1.211 - }
1.212 -
1.213 - /// \brief Move an item down into the proper box.
1.214 - void bubble_down(int index) {
1.215 - if (!upper(data[index].box, data[index].prio)) return;
1.216 - remove(index);
1.217 - int box = findDown(data[index].box, data[index].prio);
1.218 - insert(box, index);
1.219 - }
1.220 -
1.221 - /// \brief Find up the proper box for the item with the given prio.
1.222 - int findDown(int start, int pr) {
1.223 - while (upper(start, pr)) {
1.224 - if (--start < 0) throw UnderFlowPriorityError();
1.225 - }
1.226 - return start;
1.227 - }
1.228 -
1.229 - /// \brief Find the first not empty box.
1.230 - int findFirst() {
1.231 - int first = 0;
1.232 - while (boxes[first].first == -1) ++first;
1.233 - return first;
1.234 - }
1.235 -
1.236 - /// \brief Gives back the minimal prio of the box.
1.237 - int minValue(int box) {
1.238 - int min = data[boxes[box].first].prio;
1.239 - for (int k = boxes[box].first; k != -1; k = data[k].next) {
1.240 - if (data[k].prio < min) min = data[k].prio;
1.241 - }
1.242 - return min;
1.243 - }
1.244 -
1.245 - /// \brief Rearrange the items of the heap and makes the
1.246 - /// first box not empty.
1.247 - void moveDown() {
1.248 - int box = findFirst();
1.249 - if (box == 0) return;
1.250 - int min = minValue(box);
1.251 - for (int i = 0; i <= box; ++i) {
1.252 - boxes[i].min = min;
1.253 - min += boxes[i].size;
1.254 - }
1.255 - int curr = boxes[box].first, next;
1.256 - while (curr != -1) {
1.257 - next = data[curr].next;
1.258 - bubble_down(curr);
1.259 - curr = next;
1.260 - }
1.261 - }
1.262 -
1.263 - void relocate_last(int index) {
1.264 - if (index != int(data.size()) - 1) {
1.265 - data[index] = data.back();
1.266 - if (data[index].prev != -1) {
1.267 - data[data[index].prev].next = index;
1.268 - } else {
1.269 - boxes[data[index].box].first = index;
1.270 - }
1.271 - if (data[index].next != -1) {
1.272 - data[data[index].next].prev = index;
1.273 - }
1.274 - _iim[data[index].item] = index;
1.275 - }
1.276 - data.pop_back();
1.277 - }
1.278 -
1.279 - public:
1.280 -
1.281 - /// \brief Insert an item into the heap with the given priority.
1.282 - ///
1.283 - /// Adds \c i to the heap with priority \c p.
1.284 - /// \param i The item to insert.
1.285 - /// \param p The priority of the item.
1.286 - void push(const Item &i, const Prio &p) {
1.287 - int n = data.size();
1.288 - _iim.set(i, n);
1.289 - data.push_back(RadixItem(i, p));
1.290 - while (lower(boxes.size() - 1, p)) {
1.291 - extend();
1.292 - }
1.293 - int box = findDown(boxes.size() - 1, p);
1.294 - insert(box, n);
1.295 - }
1.296 -
1.297 - /// \brief Returns the item with minimum priority.
1.298 - ///
1.299 - /// This method returns the item with minimum priority.
1.300 - /// \pre The heap must be nonempty.
1.301 - Item top() const {
1.302 - const_cast<RadixHeap<ItemIntMap>&>(*this).moveDown();
1.303 - return data[boxes[0].first].item;
1.304 - }
1.305 -
1.306 - /// \brief Returns the minimum priority.
1.307 - ///
1.308 - /// It returns the minimum priority.
1.309 - /// \pre The heap must be nonempty.
1.310 - Prio prio() const {
1.311 - const_cast<RadixHeap<ItemIntMap>&>(*this).moveDown();
1.312 - return data[boxes[0].first].prio;
1.313 - }
1.314 -
1.315 - /// \brief Deletes the item with minimum priority.
1.316 - ///
1.317 - /// This method deletes the item with minimum priority.
1.318 - /// \pre The heap must be non-empty.
1.319 - void pop() {
1.320 - moveDown();
1.321 - int index = boxes[0].first;
1.322 - _iim[data[index].item] = POST_HEAP;
1.323 - remove(index);
1.324 - relocate_last(index);
1.325 - }
1.326 -
1.327 - /// \brief Deletes \c i from the heap.
1.328 - ///
1.329 - /// This method deletes item \c i from the heap, if \c i was
1.330 - /// already stored in the heap.
1.331 - /// \param i The item to erase.
1.332 - void erase(const Item &i) {
1.333 - int index = _iim[i];
1.334 - _iim[i] = POST_HEAP;
1.335 - remove(index);
1.336 - relocate_last(index);
1.337 - }
1.338 -
1.339 - /// \brief Returns the priority of \c i.
1.340 - ///
1.341 - /// This function returns the priority of item \c i.
1.342 - /// \pre \c i must be in the heap.
1.343 - /// \param i The item.
1.344 - Prio operator[](const Item &i) const {
1.345 - int idx = _iim[i];
1.346 - return data[idx].prio;
1.347 - }
1.348 -
1.349 - /// \brief \c i gets to the heap with priority \c p independently
1.350 - /// if \c i was already there.
1.351 - ///
1.352 - /// This method calls \ref push(\c i, \c p) if \c i is not stored
1.353 - /// in the heap and sets the priority of \c i to \c p otherwise.
1.354 - /// It may throw an \e UnderFlowPriorityException.
1.355 - /// \param i The item.
1.356 - /// \param p The priority.
1.357 - void set(const Item &i, const Prio &p) {
1.358 - int idx = _iim[i];
1.359 - if( idx < 0 ) {
1.360 - push(i, p);
1.361 - }
1.362 - else if( p >= data[idx].prio ) {
1.363 - data[idx].prio = p;
1.364 - bubble_up(idx);
1.365 - } else {
1.366 - data[idx].prio = p;
1.367 - bubble_down(idx);
1.368 - }
1.369 - }
1.370 -
1.371 -
1.372 - /// \brief Decreases the priority of \c i to \c p.
1.373 - ///
1.374 - /// This method decreases the priority of item \c i to \c p.
1.375 - /// \pre \c i must be stored in the heap with priority at least \c p, and
1.376 - /// \c should be greater or equal to the last removed item's priority.
1.377 - /// \param i The item.
1.378 - /// \param p The priority.
1.379 - void decrease(const Item &i, const Prio &p) {
1.380 - int idx = _iim[i];
1.381 - data[idx].prio = p;
1.382 - bubble_down(idx);
1.383 - }
1.384 -
1.385 - /// \brief Increases the priority of \c i to \c p.
1.386 - ///
1.387 - /// This method sets the priority of item \c i to \c p.
1.388 - /// \pre \c i must be stored in the heap with priority at most \c p
1.389 - /// \param i The item.
1.390 - /// \param p The priority.
1.391 - void increase(const Item &i, const Prio &p) {
1.392 - int idx = _iim[i];
1.393 - data[idx].prio = p;
1.394 - bubble_up(idx);
1.395 - }
1.396 -
1.397 - /// \brief Returns if \c item is in, has already been in, or has
1.398 - /// never been in the heap.
1.399 - ///
1.400 - /// This method returns PRE_HEAP if \c item has never been in the
1.401 - /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
1.402 - /// otherwise. In the latter case it is possible that \c item will
1.403 - /// get back to the heap again.
1.404 - /// \param i The item.
1.405 - State state(const Item &i) const {
1.406 - int s = _iim[i];
1.407 - if( s >= 0 ) s = 0;
1.408 - return State(s);
1.409 - }
1.410 -
1.411 - /// \brief Sets the state of the \c item in the heap.
1.412 - ///
1.413 - /// Sets the state of the \c item in the heap. It can be used to
1.414 - /// manually clear the heap when it is important to achive the
1.415 - /// better time complexity.
1.416 - /// \param i The item.
1.417 - /// \param st The state. It should not be \c IN_HEAP.
1.418 - void state(const Item& i, State st) {
1.419 - switch (st) {
1.420 - case POST_HEAP:
1.421 - case PRE_HEAP:
1.422 - if (state(i) == IN_HEAP) {
1.423 - erase(i);
1.424 - }
1.425 - _iim[i] = st;
1.426 - break;
1.427 - case IN_HEAP:
1.428 - break;
1.429 - }
1.430 - }
1.431 -
1.432 - }; // class RadixHeap
1.433 -
1.434 -} // namespace lemon
1.435 -
1.436 -#endif // LEMON_RADIX_HEAP_H