1.1 --- a/lemon/radix_heap.h Thu Jun 11 23:13:24 2009 +0200
1.2 +++ b/lemon/radix_heap.h Wed Jul 08 17:21:30 2009 +0200
1.3 @@ -21,7 +21,7 @@
1.4
1.5 ///\ingroup auxdat
1.6 ///\file
1.7 -///\brief Radix Heap implementation.
1.8 +///\brief Radix heap implementation.
1.9
1.10 #include <vector>
1.11 #include <lemon/error.h>
1.12 @@ -29,37 +29,35 @@
1.13 namespace lemon {
1.14
1.15
1.16 - /// \ingroup auxdata
1.17 + /// \ingroup auxdat
1.18 ///
1.19 - /// \brief A Radix Heap implementation.
1.20 + /// \brief Radix heap data structure.
1.21 ///
1.22 - /// This class implements the \e radix \e heap data structure. A \e heap
1.23 - /// is a data structure for storing items with specified values called \e
1.24 - /// priorities in such a way that finding the item with minimum priority is
1.25 - /// efficient. This heap type can store only items with \e int priority.
1.26 - /// In a heap one can change the priority of an item, add or erase an
1.27 - /// item, but the priority cannot be decreased under the last removed
1.28 - /// item's priority.
1.29 + /// This class implements the \e radix \e heap data structure.
1.30 + /// It practically conforms to the \ref concepts::Heap "heap concept",
1.31 + /// but it has some limitations due its special implementation.
1.32 + /// The type of the priorities must be \c int and the priority of an
1.33 + /// item cannot be decreased under the priority of the last removed item.
1.34 ///
1.35 - /// \param IM A read and writable Item int map, used internally
1.36 - /// to handle the cross references.
1.37 - ///
1.38 - /// \see BinHeap
1.39 - /// \see Dijkstra
1.40 + /// \tparam IM A read-writable item map with \c int values, used
1.41 + /// internally to handle the cross references.
1.42 template <typename IM>
1.43 class RadixHeap {
1.44
1.45 public:
1.46 - typedef typename IM::Key Item;
1.47 +
1.48 + /// Type of the item-int map.
1.49 + typedef IM ItemIntMap;
1.50 + /// Type of the priorities.
1.51 typedef int Prio;
1.52 - typedef IM ItemIntMap;
1.53 + /// Type of the items stored in the heap.
1.54 + typedef typename ItemIntMap::Key Item;
1.55
1.56 /// \brief Exception thrown by RadixHeap.
1.57 ///
1.58 - /// This Exception is thrown when a smaller priority
1.59 - /// is inserted into the \e RadixHeap then the last time erased.
1.60 + /// This exception is thrown when an item is inserted into a
1.61 + /// RadixHeap with a priority smaller than the last erased one.
1.62 /// \see RadixHeap
1.63 -
1.64 class UnderFlowPriorityError : public Exception {
1.65 public:
1.66 virtual const char* what() const throw() {
1.67 @@ -67,18 +65,18 @@
1.68 }
1.69 };
1.70
1.71 - /// \brief Type to represent the items states.
1.72 + /// \brief Type to represent the states of the items.
1.73 ///
1.74 - /// Each Item element have a state associated to it. It may be "in heap",
1.75 - /// "pre heap" or "post heap". The latter two are indifferent from the
1.76 + /// Each item has a state associated to it. It can be "in heap",
1.77 + /// "pre-heap" or "post-heap". The latter two are indifferent from the
1.78 /// heap's point of view, but may be useful to the user.
1.79 ///
1.80 - /// The ItemIntMap \e should be initialized in such way that it maps
1.81 - /// PRE_HEAP (-1) to any element to be put in the heap...
1.82 + /// The item-int map must be initialized in such way that it assigns
1.83 + /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
1.84 enum State {
1.85 - IN_HEAP = 0,
1.86 - PRE_HEAP = -1,
1.87 - POST_HEAP = -2
1.88 + IN_HEAP = 0, ///< = 0.
1.89 + PRE_HEAP = -1, ///< = -1.
1.90 + POST_HEAP = -2 ///< = -2.
1.91 };
1.92
1.93 private:
1.94 @@ -101,47 +99,50 @@
1.95
1.96 ItemIntMap &_iim;
1.97
1.98 + public:
1.99
1.100 - public:
1.101 - /// \brief The constructor.
1.102 + /// \brief Constructor.
1.103 ///
1.104 - /// The constructor.
1.105 - ///
1.106 - /// \param map It should be given to the constructor, since it is used
1.107 - /// internally to handle the cross references. The value of the map
1.108 - /// should be PRE_HEAP (-1) for each element.
1.109 - ///
1.110 - /// \param minimal The initial minimal value of the heap.
1.111 - /// \param capacity It determines the initial capacity of the heap.
1.112 - RadixHeap(ItemIntMap &map, int minimal = 0, int capacity = 0)
1.113 - : _iim(map) {
1.114 - boxes.push_back(RadixBox(minimal, 1));
1.115 - boxes.push_back(RadixBox(minimal + 1, 1));
1.116 - while (lower(boxes.size() - 1, capacity + minimal - 1)) {
1.117 + /// Constructor.
1.118 + /// \param map A map that assigns \c int values to the items.
1.119 + /// It is used internally to handle the cross references.
1.120 + /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
1.121 + /// \param minimum The initial minimum value of the heap.
1.122 + /// \param capacity The initial capacity of the heap.
1.123 + RadixHeap(ItemIntMap &map, int minimum = 0, int capacity = 0)
1.124 + : _iim(map)
1.125 + {
1.126 + boxes.push_back(RadixBox(minimum, 1));
1.127 + boxes.push_back(RadixBox(minimum + 1, 1));
1.128 + while (lower(boxes.size() - 1, capacity + minimum - 1)) {
1.129 extend();
1.130 }
1.131 }
1.132
1.133 - /// The number of items stored in the heap.
1.134 + /// \brief The number of items stored in the heap.
1.135 ///
1.136 - /// \brief Returns the number of items stored in the heap.
1.137 + /// This function returns the number of items stored in the heap.
1.138 int size() const { return data.size(); }
1.139 - /// \brief Checks if the heap stores no items.
1.140 +
1.141 + /// \brief Check if the heap is empty.
1.142 ///
1.143 - /// Returns \c true if and only if the heap stores no items.
1.144 + /// This function returns \c true if the heap is empty.
1.145 bool empty() const { return data.empty(); }
1.146
1.147 - /// \brief Make empty this heap.
1.148 + /// \brief Make the heap empty.
1.149 ///
1.150 - /// Make empty this heap. It does not change the cross reference
1.151 - /// map. If you want to reuse a heap what is not surely empty you
1.152 - /// should first clear the heap and after that you should set the
1.153 - /// cross reference map for each item to \c PRE_HEAP.
1.154 - void clear(int minimal = 0, int capacity = 0) {
1.155 + /// This functon makes the heap empty.
1.156 + /// It does not change the cross reference map. If you want to reuse
1.157 + /// a heap that is not surely empty, you should first clear it and
1.158 + /// then you should set the cross reference map to \c PRE_HEAP
1.159 + /// for each item.
1.160 + /// \param minimum The minimum value of the heap.
1.161 + /// \param capacity The capacity of the heap.
1.162 + void clear(int minimum = 0, int capacity = 0) {
1.163 data.clear(); boxes.clear();
1.164 - boxes.push_back(RadixBox(minimal, 1));
1.165 - boxes.push_back(RadixBox(minimal + 1, 1));
1.166 - while (lower(boxes.size() - 1, capacity + minimal - 1)) {
1.167 + boxes.push_back(RadixBox(minimum, 1));
1.168 + boxes.push_back(RadixBox(minimum + 1, 1));
1.169 + while (lower(boxes.size() - 1, capacity + minimum - 1)) {
1.170 extend();
1.171 }
1.172 }
1.173 @@ -156,7 +157,7 @@
1.174 return pr >= boxes[box].min + boxes[box].size;
1.175 }
1.176
1.177 - /// \brief Remove item from the box list.
1.178 + // Remove item from the box list
1.179 void remove(int index) {
1.180 if (data[index].prev >= 0) {
1.181 data[data[index].prev].next = data[index].next;
1.182 @@ -168,7 +169,7 @@
1.183 }
1.184 }
1.185
1.186 - /// \brief Insert item into the box list.
1.187 + // Insert item into the box list
1.188 void insert(int box, int index) {
1.189 if (boxes[box].first == -1) {
1.190 boxes[box].first = index;
1.191 @@ -182,14 +183,14 @@
1.192 data[index].box = box;
1.193 }
1.194
1.195 - /// \brief Add a new box to the box list.
1.196 + // Add a new box to the box list
1.197 void extend() {
1.198 int min = boxes.back().min + boxes.back().size;
1.199 int bs = 2 * boxes.back().size;
1.200 boxes.push_back(RadixBox(min, bs));
1.201 }
1.202
1.203 - /// \brief Move an item up into the proper box.
1.204 + // Move an item up into the proper box.
1.205 void bubble_up(int index) {
1.206 if (!lower(data[index].box, data[index].prio)) return;
1.207 remove(index);
1.208 @@ -197,7 +198,7 @@
1.209 insert(box, index);
1.210 }
1.211
1.212 - /// \brief Find up the proper box for the item with the given prio.
1.213 + // Find up the proper box for the item with the given priority
1.214 int findUp(int start, int pr) {
1.215 while (lower(start, pr)) {
1.216 if (++start == int(boxes.size())) {
1.217 @@ -207,7 +208,7 @@
1.218 return start;
1.219 }
1.220
1.221 - /// \brief Move an item down into the proper box.
1.222 + // Move an item down into the proper box
1.223 void bubble_down(int index) {
1.224 if (!upper(data[index].box, data[index].prio)) return;
1.225 remove(index);
1.226 @@ -215,7 +216,7 @@
1.227 insert(box, index);
1.228 }
1.229
1.230 - /// \brief Find up the proper box for the item with the given prio.
1.231 + // Find down the proper box for the item with the given priority
1.232 int findDown(int start, int pr) {
1.233 while (upper(start, pr)) {
1.234 if (--start < 0) throw UnderFlowPriorityError();
1.235 @@ -223,14 +224,14 @@
1.236 return start;
1.237 }
1.238
1.239 - /// \brief Find the first not empty box.
1.240 + // Find the first non-empty box
1.241 int findFirst() {
1.242 int first = 0;
1.243 while (boxes[first].first == -1) ++first;
1.244 return first;
1.245 }
1.246
1.247 - /// \brief Gives back the minimal prio of the box.
1.248 + // Gives back the minimum priority of the given box
1.249 int minValue(int box) {
1.250 int min = data[boxes[box].first].prio;
1.251 for (int k = boxes[box].first; k != -1; k = data[k].next) {
1.252 @@ -239,8 +240,7 @@
1.253 return min;
1.254 }
1.255
1.256 - /// \brief Rearrange the items of the heap and makes the
1.257 - /// first box not empty.
1.258 + // Rearrange the items of the heap and make the first box non-empty
1.259 void moveDown() {
1.260 int box = findFirst();
1.261 if (box == 0) return;
1.262 @@ -277,9 +277,12 @@
1.263
1.264 /// \brief Insert an item into the heap with the given priority.
1.265 ///
1.266 - /// Adds \c i to the heap with priority \c p.
1.267 + /// This function inserts the given item into the heap with the
1.268 + /// given priority.
1.269 /// \param i The item to insert.
1.270 /// \param p The priority of the item.
1.271 + /// \pre \e i must not be stored in the heap.
1.272 + /// \warning This method may throw an \c UnderFlowPriorityException.
1.273 void push(const Item &i, const Prio &p) {
1.274 int n = data.size();
1.275 _iim.set(i, n);
1.276 @@ -291,27 +294,27 @@
1.277 insert(box, n);
1.278 }
1.279
1.280 - /// \brief Returns the item with minimum priority.
1.281 + /// \brief Return the item having minimum priority.
1.282 ///
1.283 - /// This method returns the item with minimum priority.
1.284 - /// \pre The heap must be nonempty.
1.285 + /// This function returns the item having minimum priority.
1.286 + /// \pre The heap must be non-empty.
1.287 Item top() const {
1.288 const_cast<RadixHeap<ItemIntMap>&>(*this).moveDown();
1.289 return data[boxes[0].first].item;
1.290 }
1.291
1.292 - /// \brief Returns the minimum priority.
1.293 + /// \brief The minimum priority.
1.294 ///
1.295 - /// It returns the minimum priority.
1.296 - /// \pre The heap must be nonempty.
1.297 + /// This function returns the minimum priority.
1.298 + /// \pre The heap must be non-empty.
1.299 Prio prio() const {
1.300 const_cast<RadixHeap<ItemIntMap>&>(*this).moveDown();
1.301 return data[boxes[0].first].prio;
1.302 }
1.303
1.304 - /// \brief Deletes the item with minimum priority.
1.305 + /// \brief Remove the item having minimum priority.
1.306 ///
1.307 - /// This method deletes the item with minimum priority.
1.308 + /// This function removes the item having minimum priority.
1.309 /// \pre The heap must be non-empty.
1.310 void pop() {
1.311 moveDown();
1.312 @@ -321,11 +324,12 @@
1.313 relocate_last(index);
1.314 }
1.315
1.316 - /// \brief Deletes \c i from the heap.
1.317 + /// \brief Remove the given item from the heap.
1.318 ///
1.319 - /// This method deletes item \c i from the heap, if \c i was
1.320 - /// already stored in the heap.
1.321 - /// \param i The item to erase.
1.322 + /// This function removes the given item from the heap if it is
1.323 + /// already stored.
1.324 + /// \param i The item to delete.
1.325 + /// \pre \e i must be in the heap.
1.326 void erase(const Item &i) {
1.327 int index = _iim[i];
1.328 _iim[i] = POST_HEAP;
1.329 @@ -333,24 +337,26 @@
1.330 relocate_last(index);
1.331 }
1.332
1.333 - /// \brief Returns the priority of \c i.
1.334 + /// \brief The priority of the given item.
1.335 ///
1.336 - /// This function returns the priority of item \c i.
1.337 - /// \pre \c i must be in the heap.
1.338 + /// This function returns the priority of the given item.
1.339 /// \param i The item.
1.340 + /// \pre \e i must be in the heap.
1.341 Prio operator[](const Item &i) const {
1.342 int idx = _iim[i];
1.343 return data[idx].prio;
1.344 }
1.345
1.346 - /// \brief \c i gets to the heap with priority \c p independently
1.347 - /// if \c i was already there.
1.348 + /// \brief Set the priority of an item or insert it, if it is
1.349 + /// not stored in the heap.
1.350 ///
1.351 - /// This method calls \ref push(\c i, \c p) if \c i is not stored
1.352 - /// in the heap and sets the priority of \c i to \c p otherwise.
1.353 - /// It may throw an \e UnderFlowPriorityException.
1.354 + /// This method sets the priority of the given item if it is
1.355 + /// already stored in the heap. Otherwise it inserts the given
1.356 + /// item into the heap with the given priority.
1.357 /// \param i The item.
1.358 /// \param p The priority.
1.359 + /// \pre \e i must be in the heap.
1.360 + /// \warning This method may throw an \c UnderFlowPriorityException.
1.361 void set(const Item &i, const Prio &p) {
1.362 int idx = _iim[i];
1.363 if( idx < 0 ) {
1.364 @@ -365,39 +371,38 @@
1.365 }
1.366 }
1.367
1.368 -
1.369 - /// \brief Decreases the priority of \c i to \c p.
1.370 + /// \brief Decrease the priority of an item to the given value.
1.371 ///
1.372 - /// This method decreases the priority of item \c i to \c p.
1.373 - /// \pre \c i must be stored in the heap with priority at least \c p, and
1.374 - /// \c should be greater or equal to the last removed item's priority.
1.375 + /// This function decreases the priority of an item to the given value.
1.376 /// \param i The item.
1.377 /// \param p The priority.
1.378 + /// \pre \e i must be stored in the heap with priority at least \e p.
1.379 + /// \warning This method may throw an \c UnderFlowPriorityException.
1.380 void decrease(const Item &i, const Prio &p) {
1.381 int idx = _iim[i];
1.382 data[idx].prio = p;
1.383 bubble_down(idx);
1.384 }
1.385
1.386 - /// \brief Increases the priority of \c i to \c p.
1.387 + /// \brief Increase the priority of an item to the given value.
1.388 ///
1.389 - /// This method sets the priority of item \c i to \c p.
1.390 - /// \pre \c i must be stored in the heap with priority at most \c p
1.391 + /// This function increases the priority of an item to the given value.
1.392 /// \param i The item.
1.393 /// \param p The priority.
1.394 + /// \pre \e i must be stored in the heap with priority at most \e p.
1.395 void increase(const Item &i, const Prio &p) {
1.396 int idx = _iim[i];
1.397 data[idx].prio = p;
1.398 bubble_up(idx);
1.399 }
1.400
1.401 - /// \brief Returns if \c item is in, has already been in, or has
1.402 - /// never been in the heap.
1.403 + /// \brief Return the state of an item.
1.404 ///
1.405 - /// This method returns PRE_HEAP if \c item has never been in the
1.406 - /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
1.407 - /// otherwise. In the latter case it is possible that \c item will
1.408 - /// get back to the heap again.
1.409 + /// This method returns \c PRE_HEAP if the given item has never
1.410 + /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
1.411 + /// and \c POST_HEAP otherwise.
1.412 + /// In the latter case it is possible that the item will get back
1.413 + /// to the heap again.
1.414 /// \param i The item.
1.415 State state(const Item &i) const {
1.416 int s = _iim[i];
1.417 @@ -405,11 +410,11 @@
1.418 return State(s);
1.419 }
1.420
1.421 - /// \brief Sets the state of the \c item in the heap.
1.422 + /// \brief Set the state of an item in the heap.
1.423 ///
1.424 - /// Sets the state of the \c item in the heap. It can be used to
1.425 - /// manually clear the heap when it is important to achive the
1.426 - /// better time complexity.
1.427 + /// This function sets the state of the given item in the heap.
1.428 + /// It can be used to manually clear the heap when it is important
1.429 + /// to achive better time complexity.
1.430 /// \param i The item.
1.431 /// \param st The state. It should not be \c IN_HEAP.
1.432 void state(const Item& i, State st) {