[1699] | 1 | /* -*- C++ -*- |
---|
| 2 | * lemon/floyd_warshall.h - Part of LEMON, a generic C++ optimization library |
---|
| 3 | * |
---|
| 4 | * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
---|
| 5 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
---|
| 6 | * |
---|
| 7 | * Permission to use, modify and distribute this software is granted |
---|
| 8 | * provided that this copyright notice appears in all copies. For |
---|
| 9 | * precise terms see the accompanying LICENSE file. |
---|
| 10 | * |
---|
| 11 | * This software is provided "AS IS" with no warranty of any kind, |
---|
| 12 | * express or implied, and with no claim as to its suitability for any |
---|
| 13 | * purpose. |
---|
| 14 | * |
---|
| 15 | */ |
---|
| 16 | |
---|
| 17 | #ifndef LEMON_FLOYD_WARSHALL_H |
---|
| 18 | #define LEMON_FLOYD_WARSHALL_H |
---|
| 19 | |
---|
| 20 | ///\ingroup flowalgs |
---|
| 21 | /// \file |
---|
| 22 | /// \brief FloydWarshall algorithm. |
---|
| 23 | /// |
---|
| 24 | /// \todo getPath() should be implemented! (also for BFS and DFS) |
---|
| 25 | |
---|
| 26 | #include <lemon/list_graph.h> |
---|
| 27 | #include <lemon/graph_utils.h> |
---|
| 28 | #include <lemon/invalid.h> |
---|
| 29 | #include <lemon/error.h> |
---|
| 30 | #include <lemon/maps.h> |
---|
| 31 | |
---|
| 32 | #include <limits> |
---|
| 33 | |
---|
| 34 | namespace lemon { |
---|
| 35 | |
---|
| 36 | /// \brief Default OperationTraits for the FloydWarshall algorithm class. |
---|
| 37 | /// |
---|
| 38 | /// It defines all computational operations and constants which are |
---|
| 39 | /// used in the Floyd-Warshall algorithm. The default implementation |
---|
| 40 | /// is based on the numeric_limits class. If the numeric type does not |
---|
| 41 | /// have infinity value then the maximum value is used as extremal |
---|
| 42 | /// infinity value. |
---|
| 43 | template < |
---|
| 44 | typename Value, |
---|
| 45 | bool has_infinity = std::numeric_limits<Value>::has_infinity> |
---|
| 46 | struct FloydWarshallDefaultOperationTraits { |
---|
| 47 | /// \brief Gives back the zero value of the type. |
---|
| 48 | static Value zero() { |
---|
| 49 | return static_cast<Value>(0); |
---|
| 50 | } |
---|
| 51 | /// \brief Gives back the positive infinity value of the type. |
---|
| 52 | static Value infinity() { |
---|
| 53 | return std::numeric_limits<Value>::infinity(); |
---|
| 54 | } |
---|
| 55 | /// \brief Gives back the sum of the given two elements. |
---|
| 56 | static Value plus(const Value& left, const Value& right) { |
---|
| 57 | return left + right; |
---|
| 58 | } |
---|
| 59 | /// \brief Gives back true only if the first value less than the second. |
---|
| 60 | static bool less(const Value& left, const Value& right) { |
---|
| 61 | return left < right; |
---|
| 62 | } |
---|
| 63 | }; |
---|
| 64 | |
---|
| 65 | template <typename Value> |
---|
| 66 | struct FloydWarshallDefaultOperationTraits<Value, false> { |
---|
| 67 | static Value zero() { |
---|
| 68 | return static_cast<Value>(0); |
---|
| 69 | } |
---|
| 70 | static Value infinity() { |
---|
| 71 | return std::numeric_limits<Value>::max(); |
---|
| 72 | } |
---|
| 73 | static Value plus(const Value& left, const Value& right) { |
---|
| 74 | if (left == infinity() || right == infinity()) return infinity(); |
---|
| 75 | return left + right; |
---|
| 76 | } |
---|
| 77 | static bool less(const Value& left, const Value& right) { |
---|
| 78 | return left < right; |
---|
| 79 | } |
---|
| 80 | }; |
---|
| 81 | |
---|
| 82 | /// \brief Default traits class of FloydWarshall class. |
---|
| 83 | /// |
---|
| 84 | /// Default traits class of FloydWarshall class. |
---|
| 85 | /// \param _Graph Graph type. |
---|
| 86 | /// \param _LegthMap Type of length map. |
---|
| 87 | template<class _Graph, class _LengthMap> |
---|
| 88 | struct FloydWarshallDefaultTraits { |
---|
| 89 | /// The graph type the algorithm runs on. |
---|
| 90 | typedef _Graph Graph; |
---|
| 91 | |
---|
| 92 | /// \brief The type of the map that stores the edge lengths. |
---|
| 93 | /// |
---|
| 94 | /// The type of the map that stores the edge lengths. |
---|
| 95 | /// It must meet the \ref concept::ReadMap "ReadMap" concept. |
---|
| 96 | typedef _LengthMap LengthMap; |
---|
| 97 | |
---|
| 98 | // The type of the length of the edges. |
---|
| 99 | typedef typename _LengthMap::Value Value; |
---|
| 100 | |
---|
| 101 | /// \brief Operation traits for belmann-ford algorithm. |
---|
| 102 | /// |
---|
| 103 | /// It defines the infinity type on the given Value type |
---|
| 104 | /// and the used operation. |
---|
| 105 | /// \see FloydWarshallDefaultOperationTraits |
---|
| 106 | typedef FloydWarshallDefaultOperationTraits<Value> OperationTraits; |
---|
| 107 | |
---|
| 108 | /// \brief The type of the map that stores the last edges of the |
---|
| 109 | /// shortest paths. |
---|
| 110 | /// |
---|
| 111 | /// The type of the map that stores the last |
---|
| 112 | /// edges of the shortest paths. |
---|
| 113 | /// It must be a matrix map with \c Graph::Edge value type. |
---|
| 114 | /// |
---|
| 115 | typedef NodeMatrixMap<Graph, typename Graph::Edge> PredMap; |
---|
| 116 | |
---|
| 117 | /// \brief Instantiates a PredMap. |
---|
| 118 | /// |
---|
| 119 | /// This function instantiates a \ref PredMap. |
---|
| 120 | /// \param G is the graph, to which we would like to define the PredMap. |
---|
| 121 | /// \todo The graph alone may be insufficient for the initialization |
---|
| 122 | static PredMap *createPredMap(const _Graph& graph) { |
---|
| 123 | return new PredMap(graph); |
---|
| 124 | } |
---|
| 125 | |
---|
| 126 | /// \brief The type of the map that stores the dists of the nodes. |
---|
| 127 | /// |
---|
| 128 | /// The type of the map that stores the dists of the nodes. |
---|
| 129 | /// It must meet the \ref concept::WriteMap "WriteMap" concept. |
---|
| 130 | /// |
---|
| 131 | typedef NodeMatrixMap<Graph, Value> DistMap; |
---|
| 132 | |
---|
| 133 | /// \brief Instantiates a DistMap. |
---|
| 134 | /// |
---|
| 135 | /// This function instantiates a \ref DistMap. |
---|
| 136 | /// \param G is the graph, to which we would like to define the |
---|
| 137 | /// \ref DistMap |
---|
| 138 | static DistMap *createDistMap(const _Graph& graph) { |
---|
| 139 | return new DistMap(graph); |
---|
| 140 | } |
---|
| 141 | |
---|
| 142 | }; |
---|
| 143 | |
---|
| 144 | /// \brief FloydWarshall algorithm class. |
---|
| 145 | /// |
---|
| 146 | /// \ingroup flowalgs |
---|
| 147 | /// This class provides an efficient implementation of \c FloydWarshall |
---|
| 148 | /// algorithm. The edge lengths are passed to the algorithm using a |
---|
| 149 | /// \ref concept::ReadMap "ReadMap", so it is easy to change it to any |
---|
| 150 | /// kind of length. |
---|
| 151 | /// |
---|
| 152 | /// The type of the length is determined by the |
---|
| 153 | /// \ref concept::ReadMap::Value "Value" of the length map. |
---|
| 154 | /// |
---|
| 155 | /// \param _Graph The graph type the algorithm runs on. The default value |
---|
| 156 | /// is \ref ListGraph. The value of _Graph is not used directly by |
---|
| 157 | /// FloydWarshall, it is only passed to \ref FloydWarshallDefaultTraits. |
---|
| 158 | /// \param _LengthMap This read-only EdgeMap determines the lengths of the |
---|
| 159 | /// edges. It is read once for each edge, so the map may involve in |
---|
| 160 | /// relatively time consuming process to compute the edge length if |
---|
| 161 | /// it is necessary. The default map type is \ref |
---|
| 162 | /// concept::StaticGraph::EdgeMap "Graph::EdgeMap<int>". The value |
---|
| 163 | /// of _LengthMap is not used directly by FloydWarshall, it is only passed |
---|
| 164 | /// to \ref FloydWarshallDefaultTraits. \param _Traits Traits class to set |
---|
| 165 | /// various data types used by the algorithm. The default traits |
---|
| 166 | /// class is \ref FloydWarshallDefaultTraits |
---|
| 167 | /// "FloydWarshallDefaultTraits<_Graph,_LengthMap>". See \ref |
---|
| 168 | /// FloydWarshallDefaultTraits for the documentation of a FloydWarshall |
---|
| 169 | /// traits class. |
---|
| 170 | /// |
---|
| 171 | /// \author Balazs Dezso |
---|
| 172 | |
---|
[1710] | 173 | #ifdef DOXYGEN |
---|
| 174 | template <typename _Graph, typename _LengthMap typename _Traits > |
---|
| 175 | #else |
---|
[1699] | 176 | template <typename _Graph=ListGraph, |
---|
| 177 | typename _LengthMap=typename _Graph::template EdgeMap<int>, |
---|
| 178 | typename _Traits=FloydWarshallDefaultTraits<_Graph,_LengthMap> > |
---|
[1710] | 179 | #endif |
---|
[1699] | 180 | class FloydWarshall { |
---|
| 181 | public: |
---|
| 182 | |
---|
| 183 | /// \brief \ref Exception for uninitialized parameters. |
---|
| 184 | /// |
---|
| 185 | /// This error represents problems in the initialization |
---|
| 186 | /// of the parameters of the algorithms. |
---|
| 187 | |
---|
| 188 | class UninitializedParameter : public lemon::UninitializedParameter { |
---|
| 189 | public: |
---|
| 190 | virtual const char* exceptionName() const { |
---|
| 191 | return "lemon::FloydWarshall::UninitializedParameter"; |
---|
| 192 | } |
---|
| 193 | }; |
---|
| 194 | |
---|
| 195 | typedef _Traits Traits; |
---|
| 196 | ///The type of the underlying graph. |
---|
| 197 | typedef typename _Traits::Graph Graph; |
---|
| 198 | |
---|
| 199 | typedef typename Graph::Node Node; |
---|
| 200 | typedef typename Graph::NodeIt NodeIt; |
---|
| 201 | typedef typename Graph::Edge Edge; |
---|
| 202 | typedef typename Graph::EdgeIt EdgeIt; |
---|
| 203 | |
---|
| 204 | /// \brief The type of the length of the edges. |
---|
| 205 | typedef typename _Traits::LengthMap::Value Value; |
---|
| 206 | /// \brief The type of the map that stores the edge lengths. |
---|
| 207 | typedef typename _Traits::LengthMap LengthMap; |
---|
| 208 | /// \brief The type of the map that stores the last |
---|
| 209 | /// edges of the shortest paths. The type of the PredMap |
---|
| 210 | /// is a matrix map for Edges |
---|
| 211 | typedef typename _Traits::PredMap PredMap; |
---|
| 212 | /// \brief The type of the map that stores the dists of the nodes. |
---|
| 213 | /// The type of the DistMap is a matrix map for Values |
---|
| 214 | typedef typename _Traits::DistMap DistMap; |
---|
| 215 | /// \brief The operation traits. |
---|
| 216 | typedef typename _Traits::OperationTraits OperationTraits; |
---|
| 217 | private: |
---|
| 218 | /// Pointer to the underlying graph. |
---|
| 219 | const Graph *graph; |
---|
| 220 | /// Pointer to the length map |
---|
| 221 | const LengthMap *length; |
---|
| 222 | ///Pointer to the map of predecessors edges. |
---|
| 223 | PredMap *_pred; |
---|
| 224 | ///Indicates if \ref _pred is locally allocated (\c true) or not. |
---|
| 225 | bool local_pred; |
---|
| 226 | ///Pointer to the map of distances. |
---|
| 227 | DistMap *_dist; |
---|
| 228 | ///Indicates if \ref _dist is locally allocated (\c true) or not. |
---|
| 229 | bool local_dist; |
---|
| 230 | |
---|
| 231 | /// Creates the maps if necessary. |
---|
| 232 | void create_maps() { |
---|
| 233 | if(!_pred) { |
---|
| 234 | local_pred = true; |
---|
| 235 | _pred = Traits::createPredMap(*graph); |
---|
| 236 | } |
---|
| 237 | if(!_dist) { |
---|
| 238 | local_dist = true; |
---|
| 239 | _dist = Traits::createDistMap(*graph); |
---|
| 240 | } |
---|
| 241 | } |
---|
| 242 | |
---|
| 243 | public : |
---|
| 244 | |
---|
| 245 | /// \name Named template parameters |
---|
| 246 | |
---|
| 247 | ///@{ |
---|
| 248 | |
---|
| 249 | template <class T> |
---|
| 250 | struct DefPredMapTraits : public Traits { |
---|
| 251 | typedef T PredMap; |
---|
| 252 | static PredMap *createPredMap(const Graph& graph) { |
---|
| 253 | throw UninitializedParameter(); |
---|
| 254 | } |
---|
| 255 | }; |
---|
| 256 | |
---|
| 257 | /// \brief \ref named-templ-param "Named parameter" for setting PredMap |
---|
| 258 | /// type |
---|
| 259 | /// \ref named-templ-param "Named parameter" for setting PredMap type |
---|
| 260 | /// |
---|
| 261 | template <class T> |
---|
[1710] | 262 | struct DefPredMap |
---|
| 263 | : public FloydWarshall< Graph, LengthMap, DefPredMapTraits<T> > { |
---|
| 264 | typedef FloydWarshall< Graph, LengthMap, DefPredMapTraits<T> > Create; |
---|
| 265 | }; |
---|
[1699] | 266 | |
---|
| 267 | template <class T> |
---|
| 268 | struct DefDistMapTraits : public Traits { |
---|
| 269 | typedef T DistMap; |
---|
| 270 | static DistMap *createDistMap(const Graph& graph) { |
---|
| 271 | throw UninitializedParameter(); |
---|
| 272 | } |
---|
| 273 | }; |
---|
| 274 | /// \brief \ref named-templ-param "Named parameter" for setting DistMap |
---|
| 275 | /// type |
---|
| 276 | /// |
---|
| 277 | /// \ref named-templ-param "Named parameter" for setting DistMap type |
---|
| 278 | /// |
---|
| 279 | template <class T> |
---|
[1710] | 280 | struct DefDistMap |
---|
| 281 | : public FloydWarshall< Graph, LengthMap, DefDistMapTraits<T> > { |
---|
| 282 | typedef FloydWarshall< Graph, LengthMap, DefDistMapTraits<T> > Create; |
---|
| 283 | }; |
---|
[1699] | 284 | |
---|
| 285 | template <class T> |
---|
| 286 | struct DefOperationTraitsTraits : public Traits { |
---|
| 287 | typedef T OperationTraits; |
---|
| 288 | }; |
---|
| 289 | |
---|
| 290 | /// \brief \ref named-templ-param "Named parameter" for setting |
---|
| 291 | /// OperationTraits type |
---|
| 292 | /// |
---|
| 293 | /// \ref named-templ-param "Named parameter" for setting PredMap type |
---|
| 294 | template <class T> |
---|
[1710] | 295 | struct DefOperationTraits |
---|
[1699] | 296 | : public FloydWarshall< Graph, LengthMap, DefOperationTraitsTraits<T> > { |
---|
[1710] | 297 | typedef FloydWarshall< Graph, LengthMap, DefOperationTraitsTraits<T> > |
---|
| 298 | Create; |
---|
[1699] | 299 | }; |
---|
| 300 | |
---|
| 301 | ///@} |
---|
| 302 | |
---|
[1710] | 303 | protected: |
---|
| 304 | |
---|
| 305 | FloydWarshall() {} |
---|
| 306 | |
---|
[1699] | 307 | public: |
---|
[1710] | 308 | |
---|
| 309 | typedef FloydWarshall Create; |
---|
[1699] | 310 | |
---|
| 311 | /// \brief Constructor. |
---|
| 312 | /// |
---|
| 313 | /// \param _graph the graph the algorithm will run on. |
---|
| 314 | /// \param _length the length map used by the algorithm. |
---|
| 315 | FloydWarshall(const Graph& _graph, const LengthMap& _length) : |
---|
| 316 | graph(&_graph), length(&_length), |
---|
| 317 | _pred(0), local_pred(false), |
---|
| 318 | _dist(0), local_dist(false) {} |
---|
| 319 | |
---|
| 320 | ///Destructor. |
---|
| 321 | ~FloydWarshall() { |
---|
| 322 | if(local_pred) delete _pred; |
---|
| 323 | if(local_dist) delete _dist; |
---|
| 324 | } |
---|
| 325 | |
---|
| 326 | /// \brief Sets the length map. |
---|
| 327 | /// |
---|
| 328 | /// Sets the length map. |
---|
| 329 | /// \return \c (*this) |
---|
| 330 | FloydWarshall &lengthMap(const LengthMap &m) { |
---|
| 331 | length = &m; |
---|
| 332 | return *this; |
---|
| 333 | } |
---|
| 334 | |
---|
| 335 | /// \brief Sets the map storing the predecessor edges. |
---|
| 336 | /// |
---|
| 337 | /// Sets the map storing the predecessor edges. |
---|
| 338 | /// If you don't use this function before calling \ref run(), |
---|
| 339 | /// it will allocate one. The destuctor deallocates this |
---|
| 340 | /// automatically allocated map, of course. |
---|
| 341 | /// \return \c (*this) |
---|
| 342 | FloydWarshall &predMap(PredMap &m) { |
---|
| 343 | if(local_pred) { |
---|
| 344 | delete _pred; |
---|
| 345 | local_pred=false; |
---|
| 346 | } |
---|
| 347 | _pred = &m; |
---|
| 348 | return *this; |
---|
| 349 | } |
---|
| 350 | |
---|
| 351 | /// \brief Sets the map storing the distances calculated by the algorithm. |
---|
| 352 | /// |
---|
| 353 | /// Sets the map storing the distances calculated by the algorithm. |
---|
| 354 | /// If you don't use this function before calling \ref run(), |
---|
| 355 | /// it will allocate one. The destuctor deallocates this |
---|
| 356 | /// automatically allocated map, of course. |
---|
| 357 | /// \return \c (*this) |
---|
| 358 | FloydWarshall &distMap(DistMap &m) { |
---|
| 359 | if(local_dist) { |
---|
| 360 | delete _dist; |
---|
| 361 | local_dist=false; |
---|
| 362 | } |
---|
| 363 | _dist = &m; |
---|
| 364 | return *this; |
---|
| 365 | } |
---|
| 366 | |
---|
| 367 | ///\name Execution control |
---|
| 368 | /// The simplest way to execute the algorithm is to use |
---|
| 369 | /// one of the member functions called \c run(...). |
---|
| 370 | /// \n |
---|
| 371 | /// If you need more control on the execution, |
---|
| 372 | /// Finally \ref start() will perform the actual path |
---|
| 373 | /// computation. |
---|
| 374 | |
---|
| 375 | ///@{ |
---|
| 376 | |
---|
| 377 | /// \brief Initializes the internal data structures. |
---|
| 378 | /// |
---|
| 379 | /// Initializes the internal data structures. |
---|
| 380 | void init() { |
---|
| 381 | create_maps(); |
---|
| 382 | for (NodeIt it(*graph); it != INVALID; ++it) { |
---|
| 383 | for (NodeIt jt(*graph); jt != INVALID; ++jt) { |
---|
| 384 | _pred->set(it, jt, INVALID); |
---|
| 385 | _dist->set(it, jt, it == jt ? |
---|
| 386 | OperationTraits::zero() : OperationTraits::infinity()); |
---|
| 387 | } |
---|
| 388 | } |
---|
| 389 | for (EdgeIt it(*graph); it != INVALID; ++it) { |
---|
| 390 | Node source = graph->source(it); |
---|
| 391 | Node target = graph->target(it); |
---|
| 392 | if (OperationTraits::less((*length)[it], (*_dist)(source, target))) { |
---|
| 393 | _dist->set(source, target, (*length)[it]); |
---|
| 394 | _pred->set(source, target, it); |
---|
| 395 | } |
---|
| 396 | } |
---|
| 397 | } |
---|
| 398 | |
---|
| 399 | /// \brief Executes the algorithm. |
---|
| 400 | /// |
---|
| 401 | /// This method runs the %FloydWarshall algorithm in order to compute |
---|
| 402 | /// the shortest path to each node pairs. The algorithm |
---|
| 403 | /// computes |
---|
| 404 | /// - The shortest path tree for each node. |
---|
| 405 | /// - The distance between each node pairs. |
---|
| 406 | void start() { |
---|
| 407 | for (NodeIt kt(*graph); kt != INVALID; ++kt) { |
---|
| 408 | for (NodeIt it(*graph); it != INVALID; ++it) { |
---|
| 409 | for (NodeIt jt(*graph); jt != INVALID; ++jt) { |
---|
| 410 | Value relaxed = OperationTraits::plus((*_dist)(it, kt), |
---|
| 411 | (*_dist)(kt, jt)); |
---|
| 412 | if (OperationTraits::less(relaxed, (*_dist)(it, jt))) { |
---|
| 413 | _dist->set(it, jt, relaxed); |
---|
| 414 | _pred->set(it, jt, (*_pred)(kt, jt)); |
---|
| 415 | } |
---|
| 416 | } |
---|
| 417 | } |
---|
| 418 | } |
---|
| 419 | } |
---|
| 420 | |
---|
| 421 | /// \brief Runs %FloydWarshall algorithm. |
---|
| 422 | /// |
---|
| 423 | /// This method runs the %FloydWarshall algorithm from a each node |
---|
| 424 | /// in order to compute the shortest path to each node pairs. |
---|
| 425 | /// The algorithm computes |
---|
| 426 | /// - The shortest path tree for each node. |
---|
| 427 | /// - The distance between each node pairs. |
---|
| 428 | /// |
---|
| 429 | /// \note d.run(s) is just a shortcut of the following code. |
---|
| 430 | /// \code |
---|
| 431 | /// d.init(); |
---|
| 432 | /// d.start(); |
---|
| 433 | /// \endcode |
---|
| 434 | void run() { |
---|
| 435 | init(); |
---|
| 436 | start(); |
---|
| 437 | } |
---|
| 438 | |
---|
| 439 | ///@} |
---|
| 440 | |
---|
| 441 | /// \name Query Functions |
---|
| 442 | /// The result of the %FloydWarshall algorithm can be obtained using these |
---|
| 443 | /// functions.\n |
---|
| 444 | /// Before the use of these functions, |
---|
| 445 | /// either run() or start() must be called. |
---|
| 446 | |
---|
| 447 | ///@{ |
---|
| 448 | |
---|
| 449 | /// \brief Copies the shortest path to \c t into \c p |
---|
| 450 | /// |
---|
| 451 | /// This function copies the shortest path to \c t into \c p. |
---|
| 452 | /// If it \c t is a source itself or unreachable, then it does not |
---|
| 453 | /// alter \c p. |
---|
| 454 | /// \todo Is it the right way to handle unreachable nodes? |
---|
| 455 | /// \return Returns \c true if a path to \c t was actually copied to \c p, |
---|
| 456 | /// \c false otherwise. |
---|
| 457 | /// \sa DirPath |
---|
| 458 | template <typename Path> |
---|
| 459 | bool getPath(Path &p, Node source, Node target) { |
---|
| 460 | if (connected(source, target)) { |
---|
| 461 | p.clear(); |
---|
| 462 | typename Path::Builder b(target); |
---|
| 463 | for(b.setStartNode(target); pred(source, target) != INVALID; |
---|
| 464 | target = predNode(target)) { |
---|
| 465 | b.pushFront(pred(source, target)); |
---|
| 466 | } |
---|
| 467 | b.commit(); |
---|
| 468 | return true; |
---|
| 469 | } |
---|
| 470 | return false; |
---|
| 471 | } |
---|
| 472 | |
---|
| 473 | /// \brief The distance between two nodes. |
---|
| 474 | /// |
---|
| 475 | /// Returns the distance between two nodes. |
---|
| 476 | /// \pre \ref run() must be called before using this function. |
---|
| 477 | /// \warning If node \c v in unreachable from the root the return value |
---|
| 478 | /// of this funcion is undefined. |
---|
| 479 | Value dist(Node source, Node target) const { |
---|
| 480 | return (*_dist)(source, target); |
---|
| 481 | } |
---|
| 482 | |
---|
| 483 | /// \brief Returns the 'previous edge' of the shortest path tree. |
---|
| 484 | /// |
---|
| 485 | /// For the node \c node it returns the 'previous edge' of the shortest |
---|
| 486 | /// path tree to direction of the node \c root |
---|
| 487 | /// i.e. it returns the last edge of a shortest path from the node \c root |
---|
| 488 | /// to \c node. It is \ref INVALID if \c node is unreachable from the root |
---|
| 489 | /// or if \c node=root. The shortest path tree used here is equal to the |
---|
| 490 | /// shortest path tree used in \ref predNode(). |
---|
| 491 | /// \pre \ref run() must be called before using this function. |
---|
| 492 | /// \todo predEdge could be a better name. |
---|
| 493 | Edge pred(Node root, Node node) const { |
---|
| 494 | return (*_pred)(root, node); |
---|
| 495 | } |
---|
| 496 | |
---|
| 497 | /// \brief Returns the 'previous node' of the shortest path tree. |
---|
| 498 | /// |
---|
| 499 | /// For a node \c node it returns the 'previous node' of the shortest path |
---|
| 500 | /// tree to direction of the node \c root, i.e. it returns the last but |
---|
| 501 | /// one node from a shortest path from the \c root to \c node. It is |
---|
| 502 | /// INVALID if \c node is unreachable from the root or if \c node=root. |
---|
| 503 | /// The shortest path tree used here is equal to the |
---|
| 504 | /// shortest path tree used in \ref pred(). |
---|
| 505 | /// \pre \ref run() must be called before using this function. |
---|
| 506 | Node predNode(Node root, Node node) const { |
---|
| 507 | return (*_pred)(root, node) == INVALID ? |
---|
| 508 | INVALID : graph->source((*_pred)(root, node)); |
---|
| 509 | } |
---|
| 510 | |
---|
| 511 | /// \brief Returns a reference to the matrix node map of distances. |
---|
| 512 | /// |
---|
| 513 | /// Returns a reference to the matrix node map of distances. |
---|
| 514 | /// |
---|
| 515 | /// \pre \ref run() must be called before using this function. |
---|
| 516 | const DistMap &distMap() const { return *_dist;} |
---|
| 517 | |
---|
| 518 | /// \brief Returns a reference to the shortest path tree map. |
---|
| 519 | /// |
---|
| 520 | /// Returns a reference to the matrix node map of the edges of the |
---|
| 521 | /// shortest path tree. |
---|
| 522 | /// \pre \ref run() must be called before using this function. |
---|
| 523 | const PredMap &predMap() const { return *_pred;} |
---|
| 524 | |
---|
| 525 | /// \brief Checks if a node is reachable from the root. |
---|
| 526 | /// |
---|
| 527 | /// Returns \c true if \c v is reachable from the root. |
---|
| 528 | /// \pre \ref run() must be called before using this function. |
---|
| 529 | /// |
---|
| 530 | bool connected(Node source, Node target) { |
---|
| 531 | return (*_dist)(source, target) != OperationTraits::infinity(); |
---|
| 532 | } |
---|
| 533 | |
---|
| 534 | ///@} |
---|
| 535 | }; |
---|
| 536 | |
---|
| 537 | } //END OF NAMESPACE LEMON |
---|
| 538 | |
---|
| 539 | #endif |
---|
| 540 | |
---|