1.1 --- a/lemon/bucket_heap.h Sun Feb 21 18:55:01 2010 +0100
1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
1.3 @@ -1,567 +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_BUCKET_HEAP_H
1.23 -#define LEMON_BUCKET_HEAP_H
1.24 -
1.25 -///\ingroup auxdat
1.26 -///\file
1.27 -///\brief Bucket 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 - namespace _bucket_heap_bits {
1.36 -
1.37 - template <bool MIN>
1.38 - struct DirectionTraits {
1.39 - static bool less(int left, int right) {
1.40 - return left < right;
1.41 - }
1.42 - static void increase(int& value) {
1.43 - ++value;
1.44 - }
1.45 - };
1.46 -
1.47 - template <>
1.48 - struct DirectionTraits<false> {
1.49 - static bool less(int left, int right) {
1.50 - return left > right;
1.51 - }
1.52 - static void increase(int& value) {
1.53 - --value;
1.54 - }
1.55 - };
1.56 -
1.57 - }
1.58 -
1.59 - /// \ingroup auxdat
1.60 - ///
1.61 - /// \brief A Bucket Heap implementation.
1.62 - ///
1.63 - /// This class implements the \e bucket \e heap data structure. A \e heap
1.64 - /// is a data structure for storing items with specified values called \e
1.65 - /// priorities in such a way that finding the item with minimum priority is
1.66 - /// efficient. The bucket heap is very simple implementation, it can store
1.67 - /// only integer priorities and it stores for each priority in the
1.68 - /// \f$ [0..C) \f$ range a list of items. So it should be used only when
1.69 - /// the priorities are small. It is not intended to use as dijkstra heap.
1.70 - ///
1.71 - /// \param IM A read and write Item int map, used internally
1.72 - /// to handle the cross references.
1.73 - /// \param MIN If the given parameter is false then instead of the
1.74 - /// minimum value the maximum can be retrivied with the top() and
1.75 - /// prio() member functions.
1.76 - template <typename IM, bool MIN = true>
1.77 - class BucketHeap {
1.78 -
1.79 - public:
1.80 - /// \e
1.81 - typedef typename IM::Key Item;
1.82 - /// \e
1.83 - typedef int Prio;
1.84 - /// \e
1.85 - typedef std::pair<Item, Prio> Pair;
1.86 - /// \e
1.87 - typedef IM ItemIntMap;
1.88 -
1.89 - private:
1.90 -
1.91 - typedef _bucket_heap_bits::DirectionTraits<MIN> Direction;
1.92 -
1.93 - public:
1.94 -
1.95 - /// \brief Type to represent the items states.
1.96 - ///
1.97 - /// Each Item element have a state associated to it. It may be "in heap",
1.98 - /// "pre heap" or "post heap". The latter two are indifferent from the
1.99 - /// heap's point of view, but may be useful to the user.
1.100 - ///
1.101 - /// The item-int map must be initialized in such way that it assigns
1.102 - /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
1.103 - enum State {
1.104 - IN_HEAP = 0, ///< = 0.
1.105 - PRE_HEAP = -1, ///< = -1.
1.106 - POST_HEAP = -2 ///< = -2.
1.107 - };
1.108 -
1.109 - public:
1.110 - /// \brief The constructor.
1.111 - ///
1.112 - /// The constructor.
1.113 - /// \param map 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 - explicit BucketHeap(ItemIntMap &map) : _iim(map), _minimum(0) {}
1.117 -
1.118 - /// The number of items stored in the heap.
1.119 - ///
1.120 - /// \brief Returns the number of items stored in the heap.
1.121 - int size() const { return _data.size(); }
1.122 -
1.123 - /// \brief Checks if the heap stores no items.
1.124 - ///
1.125 - /// Returns \c true if and only if the heap stores no items.
1.126 - bool empty() const { return _data.empty(); }
1.127 -
1.128 - /// \brief Make empty this heap.
1.129 - ///
1.130 - /// Make empty this heap. It does not change the cross reference
1.131 - /// map. If you want to reuse a heap what is not surely empty you
1.132 - /// should first clear the heap and after that you should set the
1.133 - /// cross reference map for each item to \c PRE_HEAP.
1.134 - void clear() {
1.135 - _data.clear(); _first.clear(); _minimum = 0;
1.136 - }
1.137 -
1.138 - private:
1.139 -
1.140 - void relocate_last(int idx) {
1.141 - if (idx + 1 < int(_data.size())) {
1.142 - _data[idx] = _data.back();
1.143 - if (_data[idx].prev != -1) {
1.144 - _data[_data[idx].prev].next = idx;
1.145 - } else {
1.146 - _first[_data[idx].value] = idx;
1.147 - }
1.148 - if (_data[idx].next != -1) {
1.149 - _data[_data[idx].next].prev = idx;
1.150 - }
1.151 - _iim[_data[idx].item] = idx;
1.152 - }
1.153 - _data.pop_back();
1.154 - }
1.155 -
1.156 - void unlace(int idx) {
1.157 - if (_data[idx].prev != -1) {
1.158 - _data[_data[idx].prev].next = _data[idx].next;
1.159 - } else {
1.160 - _first[_data[idx].value] = _data[idx].next;
1.161 - }
1.162 - if (_data[idx].next != -1) {
1.163 - _data[_data[idx].next].prev = _data[idx].prev;
1.164 - }
1.165 - }
1.166 -
1.167 - void lace(int idx) {
1.168 - if (int(_first.size()) <= _data[idx].value) {
1.169 - _first.resize(_data[idx].value + 1, -1);
1.170 - }
1.171 - _data[idx].next = _first[_data[idx].value];
1.172 - if (_data[idx].next != -1) {
1.173 - _data[_data[idx].next].prev = idx;
1.174 - }
1.175 - _first[_data[idx].value] = idx;
1.176 - _data[idx].prev = -1;
1.177 - }
1.178 -
1.179 - public:
1.180 - /// \brief Insert a pair of item and priority into the heap.
1.181 - ///
1.182 - /// Adds \c p.first to the heap with priority \c p.second.
1.183 - /// \param p The pair to insert.
1.184 - void push(const Pair& p) {
1.185 - push(p.first, p.second);
1.186 - }
1.187 -
1.188 - /// \brief Insert an item into the heap with the given priority.
1.189 - ///
1.190 - /// Adds \c i to the heap with priority \c p.
1.191 - /// \param i The item to insert.
1.192 - /// \param p The priority of the item.
1.193 - void push(const Item &i, const Prio &p) {
1.194 - int idx = _data.size();
1.195 - _iim[i] = idx;
1.196 - _data.push_back(BucketItem(i, p));
1.197 - lace(idx);
1.198 - if (Direction::less(p, _minimum)) {
1.199 - _minimum = p;
1.200 - }
1.201 - }
1.202 -
1.203 - /// \brief Returns the item with minimum priority.
1.204 - ///
1.205 - /// This method returns the item with minimum priority.
1.206 - /// \pre The heap must be nonempty.
1.207 - Item top() const {
1.208 - while (_first[_minimum] == -1) {
1.209 - Direction::increase(_minimum);
1.210 - }
1.211 - return _data[_first[_minimum]].item;
1.212 - }
1.213 -
1.214 - /// \brief Returns the minimum priority.
1.215 - ///
1.216 - /// It returns the minimum priority.
1.217 - /// \pre The heap must be nonempty.
1.218 - Prio prio() const {
1.219 - while (_first[_minimum] == -1) {
1.220 - Direction::increase(_minimum);
1.221 - }
1.222 - return _minimum;
1.223 - }
1.224 -
1.225 - /// \brief Deletes the item with minimum priority.
1.226 - ///
1.227 - /// This method deletes the item with minimum priority from the heap.
1.228 - /// \pre The heap must be non-empty.
1.229 - void pop() {
1.230 - while (_first[_minimum] == -1) {
1.231 - Direction::increase(_minimum);
1.232 - }
1.233 - int idx = _first[_minimum];
1.234 - _iim[_data[idx].item] = -2;
1.235 - unlace(idx);
1.236 - relocate_last(idx);
1.237 - }
1.238 -
1.239 - /// \brief Deletes \c i from the heap.
1.240 - ///
1.241 - /// This method deletes item \c i from the heap, if \c i was
1.242 - /// already stored in the heap.
1.243 - /// \param i The item to erase.
1.244 - void erase(const Item &i) {
1.245 - int idx = _iim[i];
1.246 - _iim[_data[idx].item] = -2;
1.247 - unlace(idx);
1.248 - relocate_last(idx);
1.249 - }
1.250 -
1.251 -
1.252 - /// \brief Returns the priority of \c i.
1.253 - ///
1.254 - /// This function returns the priority of item \c i.
1.255 - /// \pre \c i must be in the heap.
1.256 - /// \param i The item.
1.257 - Prio operator[](const Item &i) const {
1.258 - int idx = _iim[i];
1.259 - return _data[idx].value;
1.260 - }
1.261 -
1.262 - /// \brief \c i gets to the heap with priority \c p independently
1.263 - /// if \c i was already there.
1.264 - ///
1.265 - /// This method calls \ref push(\c i, \c p) if \c i is not stored
1.266 - /// in the heap and sets the priority of \c i to \c p otherwise.
1.267 - /// \param i The item.
1.268 - /// \param p The priority.
1.269 - void set(const Item &i, const Prio &p) {
1.270 - int idx = _iim[i];
1.271 - if (idx < 0) {
1.272 - push(i, p);
1.273 - } else if (Direction::less(p, _data[idx].value)) {
1.274 - decrease(i, p);
1.275 - } else {
1.276 - increase(i, p);
1.277 - }
1.278 - }
1.279 -
1.280 - /// \brief Decreases the priority of \c i to \c p.
1.281 - ///
1.282 - /// This method decreases the priority of item \c i to \c p.
1.283 - /// \pre \c i must be stored in the heap with priority at least \c
1.284 - /// p relative to \c Compare.
1.285 - /// \param i The item.
1.286 - /// \param p The priority.
1.287 - void decrease(const Item &i, const Prio &p) {
1.288 - int idx = _iim[i];
1.289 - unlace(idx);
1.290 - _data[idx].value = p;
1.291 - if (Direction::less(p, _minimum)) {
1.292 - _minimum = p;
1.293 - }
1.294 - lace(idx);
1.295 - }
1.296 -
1.297 - /// \brief Increases the priority of \c i to \c p.
1.298 - ///
1.299 - /// This method sets the priority of item \c i to \c p.
1.300 - /// \pre \c i must be stored in the heap with priority at most \c
1.301 - /// p relative to \c Compare.
1.302 - /// \param i The item.
1.303 - /// \param p The priority.
1.304 - void increase(const Item &i, const Prio &p) {
1.305 - int idx = _iim[i];
1.306 - unlace(idx);
1.307 - _data[idx].value = p;
1.308 - lace(idx);
1.309 - }
1.310 -
1.311 - /// \brief Returns if \c item is in, has already been in, or has
1.312 - /// never been in the heap.
1.313 - ///
1.314 - /// This method returns PRE_HEAP if \c item has never been in the
1.315 - /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
1.316 - /// otherwise. In the latter case it is possible that \c item will
1.317 - /// get back to the heap again.
1.318 - /// \param i The item.
1.319 - State state(const Item &i) const {
1.320 - int idx = _iim[i];
1.321 - if (idx >= 0) idx = 0;
1.322 - return State(idx);
1.323 - }
1.324 -
1.325 - /// \brief Sets the state of the \c item in the heap.
1.326 - ///
1.327 - /// Sets the state of the \c item in the heap. It can be used to
1.328 - /// manually clear the heap when it is important to achive the
1.329 - /// better time complexity.
1.330 - /// \param i The item.
1.331 - /// \param st The state. It should not be \c IN_HEAP.
1.332 - void state(const Item& i, State st) {
1.333 - switch (st) {
1.334 - case POST_HEAP:
1.335 - case PRE_HEAP:
1.336 - if (state(i) == IN_HEAP) {
1.337 - erase(i);
1.338 - }
1.339 - _iim[i] = st;
1.340 - break;
1.341 - case IN_HEAP:
1.342 - break;
1.343 - }
1.344 - }
1.345 -
1.346 - private:
1.347 -
1.348 - struct BucketItem {
1.349 - BucketItem(const Item& _item, int _value)
1.350 - : item(_item), value(_value) {}
1.351 -
1.352 - Item item;
1.353 - int value;
1.354 -
1.355 - int prev, next;
1.356 - };
1.357 -
1.358 - ItemIntMap& _iim;
1.359 - std::vector<int> _first;
1.360 - std::vector<BucketItem> _data;
1.361 - mutable int _minimum;
1.362 -
1.363 - }; // class BucketHeap
1.364 -
1.365 - /// \ingroup auxdat
1.366 - ///
1.367 - /// \brief A Simplified Bucket Heap implementation.
1.368 - ///
1.369 - /// This class implements a simplified \e bucket \e heap data
1.370 - /// structure. It does not provide some functionality but it faster
1.371 - /// and simplier data structure than the BucketHeap. The main
1.372 - /// difference is that the BucketHeap stores for every key a double
1.373 - /// linked list while this class stores just simple lists. In the
1.374 - /// other way it does not support erasing each elements just the
1.375 - /// minimal and it does not supports key increasing, decreasing.
1.376 - ///
1.377 - /// \param IM A read and write Item int map, used internally
1.378 - /// to handle the cross references.
1.379 - /// \param MIN If the given parameter is false then instead of the
1.380 - /// minimum value the maximum can be retrivied with the top() and
1.381 - /// prio() member functions.
1.382 - ///
1.383 - /// \sa BucketHeap
1.384 - template <typename IM, bool MIN = true >
1.385 - class SimpleBucketHeap {
1.386 -
1.387 - public:
1.388 - typedef typename IM::Key Item;
1.389 - typedef int Prio;
1.390 - typedef std::pair<Item, Prio> Pair;
1.391 - typedef IM ItemIntMap;
1.392 -
1.393 - private:
1.394 -
1.395 - typedef _bucket_heap_bits::DirectionTraits<MIN> Direction;
1.396 -
1.397 - public:
1.398 -
1.399 - /// \brief Type to represent the items states.
1.400 - ///
1.401 - /// Each Item element have a state associated to it. It may be "in heap",
1.402 - /// "pre heap" or "post heap". The latter two are indifferent from the
1.403 - /// heap's point of view, but may be useful to the user.
1.404 - ///
1.405 - /// The item-int map must be initialized in such way that it assigns
1.406 - /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
1.407 - enum State {
1.408 - IN_HEAP = 0, ///< = 0.
1.409 - PRE_HEAP = -1, ///< = -1.
1.410 - POST_HEAP = -2 ///< = -2.
1.411 - };
1.412 -
1.413 - public:
1.414 -
1.415 - /// \brief The constructor.
1.416 - ///
1.417 - /// The constructor.
1.418 - /// \param map should be given to the constructor, since it is used
1.419 - /// internally to handle the cross references. The value of the map
1.420 - /// should be PRE_HEAP (-1) for each element.
1.421 - explicit SimpleBucketHeap(ItemIntMap &map)
1.422 - : _iim(map), _free(-1), _num(0), _minimum(0) {}
1.423 -
1.424 - /// \brief Returns the number of items stored in the heap.
1.425 - ///
1.426 - /// The number of items stored in the heap.
1.427 - int size() const { return _num; }
1.428 -
1.429 - /// \brief Checks if the heap stores no items.
1.430 - ///
1.431 - /// Returns \c true if and only if the heap stores no items.
1.432 - bool empty() const { return _num == 0; }
1.433 -
1.434 - /// \brief Make empty this heap.
1.435 - ///
1.436 - /// Make empty this heap. It does not change the cross reference
1.437 - /// map. If you want to reuse a heap what is not surely empty you
1.438 - /// should first clear the heap and after that you should set the
1.439 - /// cross reference map for each item to \c PRE_HEAP.
1.440 - void clear() {
1.441 - _data.clear(); _first.clear(); _free = -1; _num = 0; _minimum = 0;
1.442 - }
1.443 -
1.444 - /// \brief Insert a pair of item and priority into the heap.
1.445 - ///
1.446 - /// Adds \c p.first to the heap with priority \c p.second.
1.447 - /// \param p The pair to insert.
1.448 - void push(const Pair& p) {
1.449 - push(p.first, p.second);
1.450 - }
1.451 -
1.452 - /// \brief Insert an item into the heap with the given priority.
1.453 - ///
1.454 - /// Adds \c i to the heap with priority \c p.
1.455 - /// \param i The item to insert.
1.456 - /// \param p The priority of the item.
1.457 - void push(const Item &i, const Prio &p) {
1.458 - int idx;
1.459 - if (_free == -1) {
1.460 - idx = _data.size();
1.461 - _data.push_back(BucketItem(i));
1.462 - } else {
1.463 - idx = _free;
1.464 - _free = _data[idx].next;
1.465 - _data[idx].item = i;
1.466 - }
1.467 - _iim[i] = idx;
1.468 - if (p >= int(_first.size())) _first.resize(p + 1, -1);
1.469 - _data[idx].next = _first[p];
1.470 - _first[p] = idx;
1.471 - if (Direction::less(p, _minimum)) {
1.472 - _minimum = p;
1.473 - }
1.474 - ++_num;
1.475 - }
1.476 -
1.477 - /// \brief Returns the item with minimum priority.
1.478 - ///
1.479 - /// This method returns the item with minimum priority.
1.480 - /// \pre The heap must be nonempty.
1.481 - Item top() const {
1.482 - while (_first[_minimum] == -1) {
1.483 - Direction::increase(_minimum);
1.484 - }
1.485 - return _data[_first[_minimum]].item;
1.486 - }
1.487 -
1.488 - /// \brief Returns the minimum priority.
1.489 - ///
1.490 - /// It returns the minimum priority.
1.491 - /// \pre The heap must be nonempty.
1.492 - Prio prio() const {
1.493 - while (_first[_minimum] == -1) {
1.494 - Direction::increase(_minimum);
1.495 - }
1.496 - return _minimum;
1.497 - }
1.498 -
1.499 - /// \brief Deletes the item with minimum priority.
1.500 - ///
1.501 - /// This method deletes the item with minimum priority from the heap.
1.502 - /// \pre The heap must be non-empty.
1.503 - void pop() {
1.504 - while (_first[_minimum] == -1) {
1.505 - Direction::increase(_minimum);
1.506 - }
1.507 - int idx = _first[_minimum];
1.508 - _iim[_data[idx].item] = -2;
1.509 - _first[_minimum] = _data[idx].next;
1.510 - _data[idx].next = _free;
1.511 - _free = idx;
1.512 - --_num;
1.513 - }
1.514 -
1.515 - /// \brief Returns the priority of \c i.
1.516 - ///
1.517 - /// This function returns the priority of item \c i.
1.518 - /// \warning This operator is not a constant time function
1.519 - /// because it scans the whole data structure to find the proper
1.520 - /// value.
1.521 - /// \pre \c i must be in the heap.
1.522 - /// \param i The item.
1.523 - Prio operator[](const Item &i) const {
1.524 - for (int k = 0; k < _first.size(); ++k) {
1.525 - int idx = _first[k];
1.526 - while (idx != -1) {
1.527 - if (_data[idx].item == i) {
1.528 - return k;
1.529 - }
1.530 - idx = _data[idx].next;
1.531 - }
1.532 - }
1.533 - return -1;
1.534 - }
1.535 -
1.536 - /// \brief Returns if \c item is in, has already been in, or has
1.537 - /// never been in the heap.
1.538 - ///
1.539 - /// This method returns PRE_HEAP if \c item has never been in the
1.540 - /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
1.541 - /// otherwise. In the latter case it is possible that \c item will
1.542 - /// get back to the heap again.
1.543 - /// \param i The item.
1.544 - State state(const Item &i) const {
1.545 - int idx = _iim[i];
1.546 - if (idx >= 0) idx = 0;
1.547 - return State(idx);
1.548 - }
1.549 -
1.550 - private:
1.551 -
1.552 - struct BucketItem {
1.553 - BucketItem(const Item& _item)
1.554 - : item(_item) {}
1.555 -
1.556 - Item item;
1.557 - int next;
1.558 - };
1.559 -
1.560 - ItemIntMap& _iim;
1.561 - std::vector<int> _first;
1.562 - std::vector<BucketItem> _data;
1.563 - int _free, _num;
1.564 - mutable int _minimum;
1.565 -
1.566 - }; // class SimpleBucketHeap
1.567 -
1.568 -}
1.569 -
1.570 -#endif