1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/lemon/linear_heap.h Fri Oct 14 10:58:54 2005 +0000
1.3 @@ -0,0 +1,486 @@
1.4 +/* -*- C++ -*-
1.5 + * lemon/linear_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_LINEAR_HEAP_H
1.21 +#define LEMON_LINEAR_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 + /// \brief A Linear Heap implementation.
1.37 + ///
1.38 + /// This class implements the \e linear \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. The linear heap is very simple implementation, it can store
1.42 + /// only integer priorities and it stores for each priority in the [0..C]
1.43 + /// range a list of items. So it should be used only when the priorities
1.44 + /// are small. It is not intended to use as dijkstra heap.
1.45 + ///
1.46 + /// \param _Item Type of the items to be stored.
1.47 + /// \param _ItemIntMap A read and writable Item int map, used internally
1.48 + /// to handle the cross references.
1.49 + /// \param minimize If the given parameter is true then the heap gives back
1.50 + /// the lowest priority.
1.51 + template <typename _Item, typename _ItemIntMap, bool minimize = true >
1.52 + class LinearHeap {
1.53 +
1.54 + public:
1.55 + typedef _Item Item;
1.56 + typedef int Prio;
1.57 + typedef std::pair<Item, Prio> Pair;
1.58 + typedef _ItemIntMap ItemIntMap;
1.59 +
1.60 + /// \brief Type to represent the items states.
1.61 + ///
1.62 + /// Each Item element have a state associated to it. It may be "in heap",
1.63 + /// "pre heap" or "post heap". The latter two are indifferent from the
1.64 + /// heap's point of view, but may be useful to the user.
1.65 + ///
1.66 + /// The ItemIntMap \e should be initialized in such way that it maps
1.67 + /// PRE_HEAP (-1) to any element to be put in the heap...
1.68 + enum state_enum {
1.69 + IN_HEAP = 0,
1.70 + PRE_HEAP = -1,
1.71 + POST_HEAP = -2
1.72 + };
1.73 +
1.74 + public:
1.75 + /// \brief The constructor.
1.76 + ///
1.77 + /// The constructor.
1.78 + /// \param _index should be given to the constructor, since it is used
1.79 + /// internally to handle the cross references. The value of the map
1.80 + /// should be PRE_HEAP (-1) for each element.
1.81 + explicit LinearHeap(ItemIntMap &_index) : index(_index), minimal(0) {}
1.82 +
1.83 + /// The number of items stored in the heap.
1.84 + ///
1.85 + /// \brief Returns the number of items stored in the heap.
1.86 + int size() const { return data.size(); }
1.87 +
1.88 + /// \brief Checks if the heap stores no items.
1.89 + ///
1.90 + /// Returns \c true if and only if the heap stores no items.
1.91 + bool empty() const { return data.empty(); }
1.92 +
1.93 + /// \brief Make empty this heap.
1.94 + ///
1.95 + /// Make empty this heap.
1.96 + void clear() {
1.97 + for (int i = 0; i < (int)data.size(); ++i) {
1.98 + index[data[i].item] = -2;
1.99 + }
1.100 + data.clear(); first.clear(); minimal = 0;
1.101 + }
1.102 +
1.103 + private:
1.104 +
1.105 + void relocate_last(int idx) {
1.106 + if (idx + 1 < (int)data.size()) {
1.107 + data[idx] = data.back();
1.108 + if (data[idx].prev != -1) {
1.109 + data[data[idx].prev].next = idx;
1.110 + } else {
1.111 + first[data[idx].value] = idx;
1.112 + }
1.113 + if (data[idx].next != -1) {
1.114 + data[data[idx].next].prev = idx;
1.115 + }
1.116 + index[data[idx].item] = idx;
1.117 + }
1.118 + data.pop_back();
1.119 + }
1.120 +
1.121 + void unlace(int idx) {
1.122 + if (data[idx].prev != -1) {
1.123 + data[data[idx].prev].next = data[idx].next;
1.124 + } else {
1.125 + first[data[idx].value] = data[idx].next;
1.126 + }
1.127 + if (data[idx].next != -1) {
1.128 + data[data[idx].next].prev = data[idx].prev;
1.129 + }
1.130 + }
1.131 +
1.132 + void lace(int idx) {
1.133 + if ((int)first.size() <= data[idx].value) {
1.134 + first.resize(data[idx].value + 1, -1);
1.135 + }
1.136 + data[idx].next = first[data[idx].value];
1.137 + if (data[idx].next != -1) {
1.138 + data[data[idx].next].prev = idx;
1.139 + }
1.140 + first[data[idx].value] = idx;
1.141 + data[idx].prev = -1;
1.142 + }
1.143 +
1.144 + public:
1.145 + /// \brief Insert a pair of item and priority into the heap.
1.146 + ///
1.147 + /// Adds \c p.first to the heap with priority \c p.second.
1.148 + /// \param p The pair to insert.
1.149 + void push(const Pair& p) {
1.150 + push(p.first, p.second);
1.151 + }
1.152 +
1.153 + /// \brief Insert an item into the heap with the given priority.
1.154 + ///
1.155 + /// Adds \c i to the heap with priority \c p.
1.156 + /// \param i The item to insert.
1.157 + /// \param p The priority of the item.
1.158 + void push(const Item &i, const Prio &p) {
1.159 + int idx = data.size();
1.160 + index[i] = idx;
1.161 + data.push_back(LinearItem(i, p));
1.162 + lace(idx);
1.163 + if (p < minimal) {
1.164 + minimal = p;
1.165 + }
1.166 + }
1.167 +
1.168 + /// \brief Returns the item with minimum priority relative to \c Compare.
1.169 + ///
1.170 + /// This method returns the item with minimum priority relative to \c
1.171 + /// Compare.
1.172 + /// \pre The heap must be nonempty.
1.173 + Item top() const {
1.174 + while (first[minimal] == -1) {
1.175 + ++minimal;
1.176 + }
1.177 + return data[first[minimal]].item;
1.178 + }
1.179 +
1.180 + /// \brief Returns the minimum priority relative to \c Compare.
1.181 + ///
1.182 + /// It returns the minimum priority relative to \c Compare.
1.183 + /// \pre The heap must be nonempty.
1.184 + Prio prio() const {
1.185 + while (first[minimal] == -1) {
1.186 + ++minimal;
1.187 + }
1.188 + return minimal;
1.189 + }
1.190 +
1.191 + /// \brief Deletes the item with minimum priority relative to \c Compare.
1.192 + ///
1.193 + /// This method deletes the item with minimum priority relative to \c
1.194 + /// Compare from the heap.
1.195 + /// \pre The heap must be non-empty.
1.196 + void pop() {
1.197 + while (first[minimal] == -1) {
1.198 + ++minimal;
1.199 + }
1.200 + int idx = first[minimal];
1.201 + index[data[idx].item] = -2;
1.202 + unlace(idx);
1.203 + relocate_last(idx);
1.204 + }
1.205 +
1.206 + /// \brief Deletes \c i from the heap.
1.207 + ///
1.208 + /// This method deletes item \c i from the heap, if \c i was
1.209 + /// already stored in the heap.
1.210 + /// \param i The item to erase.
1.211 + void erase(const Item &i) {
1.212 + int idx = index[i];
1.213 + index[data[idx].item] = -2;
1.214 + unlace(idx);
1.215 + relocate_last(idx);
1.216 + }
1.217 +
1.218 +
1.219 + /// \brief Returns the priority of \c i.
1.220 + ///
1.221 + /// This function returns the priority of item \c i.
1.222 + /// \pre \c i must be in the heap.
1.223 + /// \param i The item.
1.224 + Prio operator[](const Item &i) const {
1.225 + int idx = index[i];
1.226 + return data[idx].value;
1.227 + }
1.228 +
1.229 + /// \brief \c i gets to the heap with priority \c p independently
1.230 + /// if \c i was already there.
1.231 + ///
1.232 + /// This method calls \ref push(\c i, \c p) if \c i is not stored
1.233 + /// in the heap and sets the priority of \c i to \c p otherwise.
1.234 + /// \param i The item.
1.235 + /// \param p The priority.
1.236 + void set(const Item &i, const Prio &p) {
1.237 + int idx = index[i];
1.238 + if (idx < 0) {
1.239 + push(i,p);
1.240 + } else if (p > data[idx].value) {
1.241 + increase(i, p);
1.242 + } else {
1.243 + decrease(i, p);
1.244 + }
1.245 + }
1.246 +
1.247 + /// \brief Decreases the priority of \c i to \c p.
1.248 +
1.249 + /// This method decreases the priority of item \c i to \c p.
1.250 + /// \pre \c i must be stored in the heap with priority at least \c
1.251 + /// p relative to \c Compare.
1.252 + /// \param i The item.
1.253 + /// \param p The priority.
1.254 + void decrease(const Item &i, const Prio &p) {
1.255 + int idx = index[i];
1.256 + unlace(idx);
1.257 + data[idx].value = p;
1.258 + if (p < minimal) {
1.259 + minimal = p;
1.260 + }
1.261 + lace(idx);
1.262 + }
1.263 +
1.264 + /// \brief Increases the priority of \c i to \c p.
1.265 + ///
1.266 + /// This method sets the priority of item \c i to \c p.
1.267 + /// \pre \c i must be stored in the heap with priority at most \c
1.268 + /// p relative to \c Compare.
1.269 + /// \param i The item.
1.270 + /// \param p The priority.
1.271 + void increase(const Item &i, const Prio &p) {
1.272 + int idx = index[i];
1.273 + unlace(idx);
1.274 + data[idx].value = p;
1.275 + lace(idx);
1.276 + }
1.277 +
1.278 + /// \brief Returns if \c item is in, has already been in, or has
1.279 + /// never been in the heap.
1.280 + ///
1.281 + /// This method returns PRE_HEAP if \c item has never been in the
1.282 + /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
1.283 + /// otherwise. In the latter case it is possible that \c item will
1.284 + /// get back to the heap again.
1.285 + /// \param i The item.
1.286 + state_enum state(const Item &i) const {
1.287 + int idx = index[i];
1.288 + if (idx >= 0) idx = 0;
1.289 + return state_enum(idx);
1.290 + }
1.291 +
1.292 + private:
1.293 +
1.294 + struct LinearItem {
1.295 + LinearItem(const Item& _item, int _value)
1.296 + : item(_item), value(_value) {}
1.297 +
1.298 + Item item;
1.299 + int value;
1.300 +
1.301 + int prev, next;
1.302 + };
1.303 +
1.304 + ItemIntMap& index;
1.305 + std::vector<int> first;
1.306 + std::vector<LinearItem> data;
1.307 + mutable int minimal;
1.308 +
1.309 + }; // class LinearHeap
1.310 +
1.311 +
1.312 + template <typename _Item, typename _ItemIntMap>
1.313 + class LinearHeap<_Item, _ItemIntMap, false> {
1.314 +
1.315 + public:
1.316 + typedef _Item Item;
1.317 + typedef int Prio;
1.318 + typedef std::pair<Item, Prio> Pair;
1.319 + typedef _ItemIntMap ItemIntMap;
1.320 +
1.321 + enum state_enum {
1.322 + IN_HEAP = 0,
1.323 + PRE_HEAP = -1,
1.324 + POST_HEAP = -2
1.325 + };
1.326 +
1.327 + public:
1.328 +
1.329 + explicit LinearHeap(ItemIntMap &_index) : index(_index), maximal(-1) {}
1.330 +
1.331 + int size() const { return data.size(); }
1.332 + bool empty() const { return data.empty(); }
1.333 +
1.334 + void clear() {
1.335 + for (int i = 0; i < (int)data.size(); ++i) {
1.336 + index[data[i].item] = -2;
1.337 + }
1.338 + data.clear(); first.clear(); maximal = -1;
1.339 + }
1.340 +
1.341 + private:
1.342 +
1.343 + void relocate_last(int idx) {
1.344 + if (idx + 1 != (int)data.size()) {
1.345 + data[idx] = data.back();
1.346 + if (data[idx].prev != -1) {
1.347 + data[data[idx].prev].next = idx;
1.348 + } else {
1.349 + first[data[idx].value] = idx;
1.350 + }
1.351 + if (data[idx].next != -1) {
1.352 + data[data[idx].next].prev = idx;
1.353 + }
1.354 + index[data[idx].item] = idx;
1.355 + }
1.356 + data.pop_back();
1.357 + }
1.358 +
1.359 + void unlace(int idx) {
1.360 + if (data[idx].prev != -1) {
1.361 + data[data[idx].prev].next = data[idx].next;
1.362 + } else {
1.363 + first[data[idx].value] = data[idx].next;
1.364 + }
1.365 + if (data[idx].next != -1) {
1.366 + data[data[idx].next].prev = data[idx].prev;
1.367 + }
1.368 + }
1.369 +
1.370 + void lace(int idx) {
1.371 + if ((int)first.size() <= data[idx].value) {
1.372 + first.resize(data[idx].value + 1, -1);
1.373 + }
1.374 + data[idx].next = first[data[idx].value];
1.375 + if (data[idx].next != -1) {
1.376 + data[data[idx].next].prev = idx;
1.377 + }
1.378 + first[data[idx].value] = idx;
1.379 + data[idx].prev = -1;
1.380 + }
1.381 +
1.382 + public:
1.383 +
1.384 + void push(const Pair& p) {
1.385 + push(p.first, p.second);
1.386 + }
1.387 +
1.388 + void push(const Item &i, const Prio &p) {
1.389 + int idx = data.size();
1.390 + index[i] = idx;
1.391 + data.push_back(LinearItem(i, p));
1.392 + lace(idx);
1.393 + if (data[idx].value > maximal) {
1.394 + maximal = data[idx].value;
1.395 + }
1.396 + }
1.397 +
1.398 + Item top() const {
1.399 + while (first[maximal] == -1) {
1.400 + --maximal;
1.401 + }
1.402 + return data[first[maximal]].item;
1.403 + }
1.404 +
1.405 + Prio prio() const {
1.406 + while (first[maximal] == -1) {
1.407 + --maximal;
1.408 + }
1.409 + return maximal;
1.410 + }
1.411 +
1.412 + void pop() {
1.413 + while (first[maximal] == -1) {
1.414 + --maximal;
1.415 + }
1.416 + int idx = first[maximal];
1.417 + index[data[idx].item] = -2;
1.418 + unlace(idx);
1.419 + relocate_last(idx);
1.420 + }
1.421 +
1.422 + void erase(const Item &i) {
1.423 + int idx = index[i];
1.424 + index[data[idx].item] = -2;
1.425 + unlace(idx);
1.426 + relocate_last(idx);
1.427 + }
1.428 +
1.429 + Prio operator[](const Item &i) const {
1.430 + int idx = index[i];
1.431 + return data[idx].value;
1.432 + }
1.433 +
1.434 + void set(const Item &i, const Prio &p) {
1.435 + int idx = index[i];
1.436 + if (idx < 0) {
1.437 + push(i,p);
1.438 + } else if (p > data[idx].value) {
1.439 + decrease(i, p);
1.440 + } else {
1.441 + increase(i, p);
1.442 + }
1.443 + }
1.444 +
1.445 + void decrease(const Item &i, const Prio &p) {
1.446 + int idx = index[i];
1.447 + unlace(idx);
1.448 + data[idx].value = p;
1.449 + if (p > maximal) {
1.450 + maximal = p;
1.451 + }
1.452 + lace(idx);
1.453 + }
1.454 +
1.455 + void increase(const Item &i, const Prio &p) {
1.456 + int idx = index[i];
1.457 + unlace(idx);
1.458 + data[idx].value = p;
1.459 + lace(idx);
1.460 + }
1.461 +
1.462 + state_enum state(const Item &i) const {
1.463 + int idx = index[i];
1.464 + if (idx >= 0) idx = 0;
1.465 + return state_enum(idx);
1.466 + }
1.467 +
1.468 + private:
1.469 +
1.470 + struct LinearItem {
1.471 + LinearItem(const Item& _item, int _value)
1.472 + : item(_item), value(_value) {}
1.473 +
1.474 + Item item;
1.475 + int value;
1.476 +
1.477 + int prev, next;
1.478 + };
1.479 +
1.480 + ItemIntMap& index;
1.481 + std::vector<int> first;
1.482 + std::vector<LinearItem> data;
1.483 + mutable int maximal;
1.484 +
1.485 + }; // class LinearHeap
1.486 +
1.487 +}
1.488 +
1.489 +#endif