COIN-OR::LEMON - Graph Library

source: lemon-1.2/lemon/dijkstra.h @ 257:8d76a7bf9961

Last change on this file since 257:8d76a7bf9961 was 257:8d76a7bf9961, checked in by Peter Kovacs <kpeter@…>, 11 years ago

Rename Def* to Set* in Bfs, Dfs, Dijkstra (ticket #134)

File size: 42.0 KB
Line 
1/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library.
4 *
5 * Copyright (C) 2003-2008
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19#ifndef LEMON_DIJKSTRA_H
20#define LEMON_DIJKSTRA_H
21
22///\ingroup shortest_path
23///\file
24///\brief Dijkstra algorithm.
25
26#include <limits>
27#include <lemon/list_graph.h>
28#include <lemon/bin_heap.h>
29#include <lemon/bits/path_dump.h>
30#include <lemon/core.h>
31#include <lemon/error.h>
32#include <lemon/maps.h>
33
34namespace lemon {
35
36  /// \brief Default operation traits for the Dijkstra algorithm class.
37  ///
38  /// This operation traits class defines all computational operations and
39  /// constants which are used in the Dijkstra algorithm.
40  template <typename Value>
41  struct DijkstraDefaultOperationTraits {
42    /// \brief Gives back the zero value of the type.
43    static Value zero() {
44      return static_cast<Value>(0);
45    }
46    /// \brief Gives back the sum of the given two elements.
47    static Value plus(const Value& left, const Value& right) {
48      return left + right;
49    }
50    /// \brief Gives back true only if the first value is less than the second.
51    static bool less(const Value& left, const Value& right) {
52      return left < right;
53    }
54  };
55
56  /// \brief Widest path operation traits for the Dijkstra algorithm class.
57  ///
58  /// This operation traits class defines all computational operations and
59  /// constants which are used in the Dijkstra algorithm for widest path
60  /// computation.
61  ///
62  /// \see DijkstraDefaultOperationTraits
63  template <typename Value>
64  struct DijkstraWidestPathOperationTraits {
65    /// \brief Gives back the maximum value of the type.
66    static Value zero() {
67      return std::numeric_limits<Value>::max();
68    }
69    /// \brief Gives back the minimum of the given two elements.
70    static Value plus(const Value& left, const Value& right) {
71      return std::min(left, right);
72    }
73    /// \brief Gives back true only if the first value is less than the second.
74    static bool less(const Value& left, const Value& right) {
75      return left < right;
76    }
77  };
78
79  ///Default traits class of Dijkstra class.
80
81  ///Default traits class of Dijkstra class.
82  ///\tparam GR The type of the digraph.
83  ///\tparam LM The type of the length map.
84  template<class GR, class LM>
85  struct DijkstraDefaultTraits
86  {
87    ///The type of the digraph the algorithm runs on.
88    typedef GR Digraph;
89
90    ///The type of the map that stores the arc lengths.
91
92    ///The type of the map that stores the arc lengths.
93    ///It must meet the \ref concepts::ReadMap "ReadMap" concept.
94    typedef LM LengthMap;
95    ///The type of the length of the arcs.
96    typedef typename LM::Value Value;
97
98    /// Operation traits for Dijkstra algorithm.
99
100    /// This class defines the operations that are used in the algorithm.
101    /// \see DijkstraDefaultOperationTraits
102    typedef DijkstraDefaultOperationTraits<Value> OperationTraits;
103
104    /// The cross reference type used by the heap.
105
106    /// The cross reference type used by the heap.
107    /// Usually it is \c Digraph::NodeMap<int>.
108    typedef typename Digraph::template NodeMap<int> HeapCrossRef;
109    ///Instantiates a \ref HeapCrossRef.
110
111    ///This function instantiates a \ref HeapCrossRef.
112    /// \param g is the digraph, to which we would like to define the
113    /// \ref HeapCrossRef.
114    static HeapCrossRef *createHeapCrossRef(const Digraph &g)
115    {
116      return new HeapCrossRef(g);
117    }
118
119    ///The heap type used by the Dijkstra algorithm.
120
121    ///The heap type used by the Dijkstra algorithm.
122    ///
123    ///\sa BinHeap
124    ///\sa Dijkstra
125    typedef BinHeap<typename LM::Value, HeapCrossRef, std::less<Value> > Heap;
126    ///Instantiates a \ref Heap.
127
128    ///This function instantiates a \ref Heap.
129    static Heap *createHeap(HeapCrossRef& r)
130    {
131      return new Heap(r);
132    }
133
134    ///\brief The type of the map that stores the predecessor
135    ///arcs of the shortest paths.
136    ///
137    ///The type of the map that stores the predecessor
138    ///arcs of the shortest paths.
139    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
140    typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
141    ///Instantiates a \ref PredMap.
142
143    ///This function instantiates a \ref PredMap.
144    ///\param g is the digraph, to which we would like to define the
145    ///\ref PredMap.
146    ///\todo The digraph alone may be insufficient for the initialization
147    static PredMap *createPredMap(const Digraph &g)
148    {
149      return new PredMap(g);
150    }
151
152    ///The type of the map that indicates which nodes are processed.
153
154    ///The type of the map that indicates which nodes are processed.
155    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
156    ///By default it is a NullMap.
157    ///\todo If it is set to a real map,
158    ///Dijkstra::processed() should read this.
159    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
160    ///Instantiates a \ref ProcessedMap.
161
162    ///This function instantiates a \ref ProcessedMap.
163    ///\param g is the digraph, to which
164    ///we would like to define the \ref ProcessedMap
165#ifdef DOXYGEN
166    static ProcessedMap *createProcessedMap(const Digraph &g)
167#else
168    static ProcessedMap *createProcessedMap(const Digraph &)
169#endif
170    {
171      return new ProcessedMap();
172    }
173
174    ///The type of the map that stores the distances of the nodes.
175
176    ///The type of the map that stores the distances of the nodes.
177    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
178    typedef typename Digraph::template NodeMap<typename LM::Value> DistMap;
179    ///Instantiates a \ref DistMap.
180
181    ///This function instantiates a \ref DistMap.
182    ///\param g is the digraph, to which we would like to define
183    ///the \ref DistMap
184    static DistMap *createDistMap(const Digraph &g)
185    {
186      return new DistMap(g);
187    }
188  };
189
190  ///%Dijkstra algorithm class.
191
192  /// \ingroup shortest_path
193  ///This class provides an efficient implementation of the %Dijkstra algorithm.
194  ///
195  ///The arc lengths are passed to the algorithm using a
196  ///\ref concepts::ReadMap "ReadMap",
197  ///so it is easy to change it to any kind of length.
198  ///The type of the length is determined by the
199  ///\ref concepts::ReadMap::Value "Value" of the length map.
200  ///It is also possible to change the underlying priority heap.
201  ///
202  ///There is also a \ref dijkstra() "function type interface" for the
203  ///%Dijkstra algorithm, which is convenient in the simplier cases and
204  ///it can be used easier.
205  ///
206  ///\tparam GR The type of the digraph the algorithm runs on.
207  ///The default value is \ref ListDigraph.
208  ///The value of GR is not used directly by \ref Dijkstra, it is only
209  ///passed to \ref DijkstraDefaultTraits.
210  ///\tparam LM A readable arc map that determines the lengths of the
211  ///arcs. It is read once for each arc, so the map may involve in
212  ///relatively time consuming process to compute the arc lengths if
213  ///it is necessary. The default map type is \ref
214  ///concepts::Digraph::ArcMap "Digraph::ArcMap<int>".
215  ///The value of LM is not used directly by \ref Dijkstra, it is only
216  ///passed to \ref DijkstraDefaultTraits.
217  ///\tparam TR Traits class to set various data types used by the algorithm.
218  ///The default traits class is \ref DijkstraDefaultTraits
219  ///"DijkstraDefaultTraits<GR,LM>". See \ref DijkstraDefaultTraits
220  ///for the documentation of a Dijkstra traits class.
221#ifdef DOXYGEN
222  template <typename GR, typename LM, typename TR>
223#else
224  template <typename GR=ListDigraph,
225            typename LM=typename GR::template ArcMap<int>,
226            typename TR=DijkstraDefaultTraits<GR,LM> >
227#endif
228  class Dijkstra {
229  public:
230    ///\ref Exception for uninitialized parameters.
231
232    ///This error represents problems in the initialization of the
233    ///parameters of the algorithm.
234    class UninitializedParameter : public lemon::UninitializedParameter {
235    public:
236      virtual const char* what() const throw() {
237        return "lemon::Dijkstra::UninitializedParameter";
238      }
239    };
240
241    ///The type of the digraph the algorithm runs on.
242    typedef typename TR::Digraph Digraph;
243
244    ///The type of the length of the arcs.
245    typedef typename TR::LengthMap::Value Value;
246    ///The type of the map that stores the arc lengths.
247    typedef typename TR::LengthMap LengthMap;
248    ///\brief The type of the map that stores the predecessor arcs of the
249    ///shortest paths.
250    typedef typename TR::PredMap PredMap;
251    ///The type of the map that stores the distances of the nodes.
252    typedef typename TR::DistMap DistMap;
253    ///The type of the map that indicates which nodes are processed.
254    typedef typename TR::ProcessedMap ProcessedMap;
255    ///The type of the paths.
256    typedef PredMapPath<Digraph, PredMap> Path;
257    ///The cross reference type used for the current heap.
258    typedef typename TR::HeapCrossRef HeapCrossRef;
259    ///The heap type used by the algorithm.
260    typedef typename TR::Heap Heap;
261    ///The operation traits class.
262    typedef typename TR::OperationTraits OperationTraits;
263
264    ///The traits class.
265    typedef TR Traits;
266
267  private:
268
269    typedef typename Digraph::Node Node;
270    typedef typename Digraph::NodeIt NodeIt;
271    typedef typename Digraph::Arc Arc;
272    typedef typename Digraph::OutArcIt OutArcIt;
273
274    //Pointer to the underlying digraph.
275    const Digraph *G;
276    //Pointer to the length map.
277    const LengthMap *length;
278    //Pointer to the map of predecessors arcs.
279    PredMap *_pred;
280    //Indicates if _pred is locally allocated (true) or not.
281    bool local_pred;
282    //Pointer to the map of distances.
283    DistMap *_dist;
284    //Indicates if _dist is locally allocated (true) or not.
285    bool local_dist;
286    //Pointer to the map of processed status of the nodes.
287    ProcessedMap *_processed;
288    //Indicates if _processed is locally allocated (true) or not.
289    bool local_processed;
290    //Pointer to the heap cross references.
291    HeapCrossRef *_heap_cross_ref;
292    //Indicates if _heap_cross_ref is locally allocated (true) or not.
293    bool local_heap_cross_ref;
294    //Pointer to the heap.
295    Heap *_heap;
296    //Indicates if _heap is locally allocated (true) or not.
297    bool local_heap;
298
299    ///Creates the maps if necessary.
300    ///\todo Better memory allocation (instead of new).
301    void create_maps()
302    {
303      if(!_pred) {
304        local_pred = true;
305        _pred = Traits::createPredMap(*G);
306      }
307      if(!_dist) {
308        local_dist = true;
309        _dist = Traits::createDistMap(*G);
310      }
311      if(!_processed) {
312        local_processed = true;
313        _processed = Traits::createProcessedMap(*G);
314      }
315      if (!_heap_cross_ref) {
316        local_heap_cross_ref = true;
317        _heap_cross_ref = Traits::createHeapCrossRef(*G);
318      }
319      if (!_heap) {
320        local_heap = true;
321        _heap = Traits::createHeap(*_heap_cross_ref);
322      }
323    }
324
325  public:
326
327    typedef Dijkstra Create;
328
329    ///\name Named template parameters
330
331    ///@{
332
333    template <class T>
334    struct SetPredMapTraits : public Traits {
335      typedef T PredMap;
336      static PredMap *createPredMap(const Digraph &)
337      {
338        throw UninitializedParameter();
339      }
340    };
341    ///\brief \ref named-templ-param "Named parameter" for setting
342    ///\ref PredMap type.
343    ///
344    ///\ref named-templ-param "Named parameter" for setting
345    ///\ref PredMap type.
346    template <class T>
347    struct SetPredMap
348      : public Dijkstra< Digraph, LengthMap, SetPredMapTraits<T> > {
349      typedef Dijkstra< Digraph, LengthMap, SetPredMapTraits<T> > Create;
350    };
351
352    template <class T>
353    struct SetDistMapTraits : public Traits {
354      typedef T DistMap;
355      static DistMap *createDistMap(const Digraph &)
356      {
357        throw UninitializedParameter();
358      }
359    };
360    ///\brief \ref named-templ-param "Named parameter" for setting
361    ///\ref DistMap type.
362    ///
363    ///\ref named-templ-param "Named parameter" for setting
364    ///\ref DistMap type.
365    template <class T>
366    struct SetDistMap
367      : public Dijkstra< Digraph, LengthMap, SetDistMapTraits<T> > {
368      typedef Dijkstra< Digraph, LengthMap, SetDistMapTraits<T> > Create;
369    };
370
371    template <class T>
372    struct SetProcessedMapTraits : public Traits {
373      typedef T ProcessedMap;
374      static ProcessedMap *createProcessedMap(const Digraph &)
375      {
376        throw UninitializedParameter();
377      }
378    };
379    ///\brief \ref named-templ-param "Named parameter" for setting
380    ///\ref ProcessedMap type.
381    ///
382    ///\ref named-templ-param "Named parameter" for setting
383    ///\ref ProcessedMap type.
384    template <class T>
385    struct SetProcessedMap
386      : public Dijkstra< Digraph, LengthMap, SetProcessedMapTraits<T> > {
387      typedef Dijkstra< Digraph, LengthMap, SetProcessedMapTraits<T> > Create;
388    };
389
390    struct SetStandardProcessedMapTraits : public Traits {
391      typedef typename Digraph::template NodeMap<bool> ProcessedMap;
392      static ProcessedMap *createProcessedMap(const Digraph &g)
393      {
394        return new ProcessedMap(g);
395      }
396    };
397    ///\brief \ref named-templ-param "Named parameter" for setting
398    ///\ref ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
399    ///
400    ///\ref named-templ-param "Named parameter" for setting
401    ///\ref ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
402    ///If you don't set it explicitly, it will be automatically allocated.
403    struct SetStandardProcessedMap
404      : public Dijkstra< Digraph, LengthMap, SetStandardProcessedMapTraits > {
405      typedef Dijkstra< Digraph, LengthMap, SetStandardProcessedMapTraits >
406      Create;
407    };
408
409    template <class H, class CR>
410    struct SetHeapTraits : public Traits {
411      typedef CR HeapCrossRef;
412      typedef H Heap;
413      static HeapCrossRef *createHeapCrossRef(const Digraph &) {
414        throw UninitializedParameter();
415      }
416      static Heap *createHeap(HeapCrossRef &)
417      {
418        throw UninitializedParameter();
419      }
420    };
421    ///\brief \ref named-templ-param "Named parameter" for setting
422    ///heap and cross reference type
423    ///
424    ///\ref named-templ-param "Named parameter" for setting heap and cross
425    ///reference type.
426    template <class H, class CR = typename Digraph::template NodeMap<int> >
427    struct SetHeap
428      : public Dijkstra< Digraph, LengthMap, SetHeapTraits<H, CR> > {
429      typedef Dijkstra< Digraph, LengthMap, SetHeapTraits<H, CR> > Create;
430    };
431
432    template <class H, class CR>
433    struct SetStandardHeapTraits : public Traits {
434      typedef CR HeapCrossRef;
435      typedef H Heap;
436      static HeapCrossRef *createHeapCrossRef(const Digraph &G) {
437        return new HeapCrossRef(G);
438      }
439      static Heap *createHeap(HeapCrossRef &R)
440      {
441        return new Heap(R);
442      }
443    };
444    ///\brief \ref named-templ-param "Named parameter" for setting
445    ///heap and cross reference type with automatic allocation
446    ///
447    ///\ref named-templ-param "Named parameter" for setting heap and cross
448    ///reference type. It can allocate the heap and the cross reference
449    ///object if the cross reference's constructor waits for the digraph as
450    ///parameter and the heap's constructor waits for the cross reference.
451    template <class H, class CR = typename Digraph::template NodeMap<int> >
452    struct SetStandardHeap
453      : public Dijkstra< Digraph, LengthMap, SetStandardHeapTraits<H, CR> > {
454      typedef Dijkstra< Digraph, LengthMap, SetStandardHeapTraits<H, CR> >
455      Create;
456    };
457
458    template <class T>
459    struct SetOperationTraitsTraits : public Traits {
460      typedef T OperationTraits;
461    };
462
463    /// \brief \ref named-templ-param "Named parameter" for setting
464    ///\ref OperationTraits type
465    ///
466    ///\ref named-templ-param "Named parameter" for setting
467    ///\ref OperationTraits type.
468    template <class T>
469    struct SetOperationTraits
470      : public Dijkstra<Digraph, LengthMap, SetOperationTraitsTraits<T> > {
471      typedef Dijkstra<Digraph, LengthMap, SetOperationTraitsTraits<T> >
472      Create;
473    };
474
475    ///@}
476
477  protected:
478
479    Dijkstra() {}
480
481  public:
482
483    ///Constructor.
484
485    ///Constructor.
486    ///\param _g The digraph the algorithm runs on.
487    ///\param _length The length map used by the algorithm.
488    Dijkstra(const Digraph& _g, const LengthMap& _length) :
489      G(&_g), length(&_length),
490      _pred(NULL), local_pred(false),
491      _dist(NULL), local_dist(false),
492      _processed(NULL), local_processed(false),
493      _heap_cross_ref(NULL), local_heap_cross_ref(false),
494      _heap(NULL), local_heap(false)
495    { }
496
497    ///Destructor.
498    ~Dijkstra()
499    {
500      if(local_pred) delete _pred;
501      if(local_dist) delete _dist;
502      if(local_processed) delete _processed;
503      if(local_heap_cross_ref) delete _heap_cross_ref;
504      if(local_heap) delete _heap;
505    }
506
507    ///Sets the length map.
508
509    ///Sets the length map.
510    ///\return <tt> (*this) </tt>
511    Dijkstra &lengthMap(const LengthMap &m)
512    {
513      length = &m;
514      return *this;
515    }
516
517    ///Sets the map that stores the predecessor arcs.
518
519    ///Sets the map that stores the predecessor arcs.
520    ///If you don't use this function before calling \ref run(),
521    ///it will allocate one. The destructor deallocates this
522    ///automatically allocated map, of course.
523    ///\return <tt> (*this) </tt>
524    Dijkstra &predMap(PredMap &m)
525    {
526      if(local_pred) {
527        delete _pred;
528        local_pred=false;
529      }
530      _pred = &m;
531      return *this;
532    }
533
534    ///Sets the map that indicates which nodes are processed.
535
536    ///Sets the map that indicates which nodes are processed.
537    ///If you don't use this function before calling \ref run(),
538    ///it will allocate one. The destructor deallocates this
539    ///automatically allocated map, of course.
540    ///\return <tt> (*this) </tt>
541    Dijkstra &processedMap(ProcessedMap &m)
542    {
543      if(local_processed) {
544        delete _processed;
545        local_processed=false;
546      }
547      _processed = &m;
548      return *this;
549    }
550
551    ///Sets the map that stores the distances of the nodes.
552
553    ///Sets the map that stores the distances of the nodes calculated by the
554    ///algorithm.
555    ///If you don't use this function before calling \ref run(),
556    ///it will allocate one. The destructor deallocates this
557    ///automatically allocated map, of course.
558    ///\return <tt> (*this) </tt>
559    Dijkstra &distMap(DistMap &m)
560    {
561      if(local_dist) {
562        delete _dist;
563        local_dist=false;
564      }
565      _dist = &m;
566      return *this;
567    }
568
569    ///Sets the heap and the cross reference used by algorithm.
570
571    ///Sets the heap and the cross reference used by algorithm.
572    ///If you don't use this function before calling \ref run(),
573    ///it will allocate one. The destructor deallocates this
574    ///automatically allocated heap and cross reference, of course.
575    ///\return <tt> (*this) </tt>
576    Dijkstra &heap(Heap& hp, HeapCrossRef &cr)
577    {
578      if(local_heap_cross_ref) {
579        delete _heap_cross_ref;
580        local_heap_cross_ref=false;
581      }
582      _heap_cross_ref = &cr;
583      if(local_heap) {
584        delete _heap;
585        local_heap=false;
586      }
587      _heap = &hp;
588      return *this;
589    }
590
591  private:
592
593    void finalizeNodeData(Node v,Value dst)
594    {
595      _processed->set(v,true);
596      _dist->set(v, dst);
597    }
598
599  public:
600
601    ///\name Execution control
602    ///The simplest way to execute the algorithm is to use one of the
603    ///member functions called \ref lemon::Dijkstra::run() "run()".
604    ///\n
605    ///If you need more control on the execution, first you must call
606    ///\ref lemon::Dijkstra::init() "init()", then you can add several
607    ///source nodes with \ref lemon::Dijkstra::addSource() "addSource()".
608    ///Finally \ref lemon::Dijkstra::start() "start()" will perform the
609    ///actual path computation.
610
611    ///@{
612
613    ///Initializes the internal data structures.
614
615    ///Initializes the internal data structures.
616    ///
617    void init()
618    {
619      create_maps();
620      _heap->clear();
621      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
622        _pred->set(u,INVALID);
623        _processed->set(u,false);
624        _heap_cross_ref->set(u,Heap::PRE_HEAP);
625      }
626    }
627
628    ///Adds a new source node.
629
630    ///Adds a new source node to the priority heap.
631    ///The optional second parameter is the initial distance of the node.
632    ///
633    ///The function checks if the node has already been added to the heap and
634    ///it is pushed to the heap only if either it was not in the heap
635    ///or the shortest path found till then is shorter than \c dst.
636    void addSource(Node s,Value dst=OperationTraits::zero())
637    {
638      if(_heap->state(s) != Heap::IN_HEAP) {
639        _heap->push(s,dst);
640      } else if(OperationTraits::less((*_heap)[s], dst)) {
641        _heap->set(s,dst);
642        _pred->set(s,INVALID);
643      }
644    }
645
646    ///Processes the next node in the priority heap
647
648    ///Processes the next node in the priority heap.
649    ///
650    ///\return The processed node.
651    ///
652    ///\warning The priority heap must not be empty.
653    Node processNextNode()
654    {
655      Node v=_heap->top();
656      Value oldvalue=_heap->prio();
657      _heap->pop();
658      finalizeNodeData(v,oldvalue);
659
660      for(OutArcIt e(*G,v); e!=INVALID; ++e) {
661        Node w=G->target(e);
662        switch(_heap->state(w)) {
663        case Heap::PRE_HEAP:
664          _heap->push(w,OperationTraits::plus(oldvalue, (*length)[e]));
665          _pred->set(w,e);
666          break;
667        case Heap::IN_HEAP:
668          {
669            Value newvalue = OperationTraits::plus(oldvalue, (*length)[e]);
670            if ( OperationTraits::less(newvalue, (*_heap)[w]) ) {
671              _heap->decrease(w, newvalue);
672              _pred->set(w,e);
673            }
674          }
675          break;
676        case Heap::POST_HEAP:
677          break;
678        }
679      }
680      return v;
681    }
682
683    ///The next node to be processed.
684
685    ///Returns the next node to be processed or \c INVALID if the
686    ///priority heap is empty.
687    Node nextNode() const
688    {
689      return !_heap->empty()?_heap->top():INVALID;
690    }
691
692    ///\brief Returns \c false if there are nodes
693    ///to be processed.
694    ///
695    ///Returns \c false if there are nodes
696    ///to be processed in the priority heap.
697    bool emptyQueue() const { return _heap->empty(); }
698
699    ///Returns the number of the nodes to be processed in the priority heap
700
701    ///Returns the number of the nodes to be processed in the priority heap.
702    ///
703    int queueSize() const { return _heap->size(); }
704
705    ///Executes the algorithm.
706
707    ///Executes the algorithm.
708    ///
709    ///This method runs the %Dijkstra algorithm from the root node(s)
710    ///in order to compute the shortest path to each node.
711    ///
712    ///The algorithm computes
713    ///- the shortest path tree (forest),
714    ///- the distance of each node from the root(s).
715    ///
716    ///\pre init() must be called and at least one root node should be
717    ///added with addSource() before using this function.
718    ///
719    ///\note <tt>d.start()</tt> is just a shortcut of the following code.
720    ///\code
721    ///  while ( !d.emptyQueue() ) {
722    ///    d.processNextNode();
723    ///  }
724    ///\endcode
725    void start()
726    {
727      while ( !emptyQueue() ) processNextNode();
728    }
729
730    ///Executes the algorithm until the given target node is reached.
731
732    ///Executes the algorithm until the given target node is reached.
733    ///
734    ///This method runs the %Dijkstra algorithm from the root node(s)
735    ///in order to compute the shortest path to \c dest.
736    ///
737    ///The algorithm computes
738    ///- the shortest path to \c dest,
739    ///- the distance of \c dest from the root(s).
740    ///
741    ///\pre init() must be called and at least one root node should be
742    ///added with addSource() before using this function.
743    void start(Node dest)
744    {
745      while ( !_heap->empty() && _heap->top()!=dest ) processNextNode();
746      if ( !_heap->empty() ) finalizeNodeData(_heap->top(),_heap->prio());
747    }
748
749    ///Executes the algorithm until a condition is met.
750
751    ///Executes the algorithm until a condition is met.
752    ///
753    ///This method runs the %Dijkstra algorithm from the root node(s) in
754    ///order to compute the shortest path to a node \c v with
755    /// <tt>nm[v]</tt> true, if such a node can be found.
756    ///
757    ///\param nm A \c bool (or convertible) node map. The algorithm
758    ///will stop when it reaches a node \c v with <tt>nm[v]</tt> true.
759    ///
760    ///\return The reached node \c v with <tt>nm[v]</tt> true or
761    ///\c INVALID if no such node was found.
762    ///
763    ///\pre init() must be called and at least one root node should be
764    ///added with addSource() before using this function.
765    template<class NodeBoolMap>
766    Node start(const NodeBoolMap &nm)
767    {
768      while ( !_heap->empty() && !nm[_heap->top()] ) processNextNode();
769      if ( _heap->empty() ) return INVALID;
770      finalizeNodeData(_heap->top(),_heap->prio());
771      return _heap->top();
772    }
773
774    ///Runs the algorithm from the given node.
775
776    ///This method runs the %Dijkstra algorithm from node \c s
777    ///in order to compute the shortest path to each node.
778    ///
779    ///The algorithm computes
780    ///- the shortest path tree,
781    ///- the distance of each node from the root.
782    ///
783    ///\note <tt>d.run(s)</tt> is just a shortcut of the following code.
784    ///\code
785    ///  d.init();
786    ///  d.addSource(s);
787    ///  d.start();
788    ///\endcode
789    void run(Node s) {
790      init();
791      addSource(s);
792      start();
793    }
794
795    ///Finds the shortest path between \c s and \c t.
796
797    ///This method runs the %Dijkstra algorithm from node \c s
798    ///in order to compute the shortest path to \c t.
799    ///
800    ///\return The length of the shortest <tt>s</tt>--<tt>t</tt> path,
801    ///if \c t is reachable form \c s, \c 0 otherwise.
802    ///
803    ///\note Apart from the return value, <tt>d.run(s,t)</tt> is just a
804    ///shortcut of the following code.
805    ///\code
806    ///  d.init();
807    ///  d.addSource(s);
808    ///  d.start(t);
809    ///\endcode
810    Value run(Node s,Node t) {
811      init();
812      addSource(s);
813      start(t);
814      return (*_pred)[t]==INVALID?OperationTraits::zero():(*_dist)[t];
815    }
816
817    ///@}
818
819    ///\name Query Functions
820    ///The result of the %Dijkstra algorithm can be obtained using these
821    ///functions.\n
822    ///Either \ref lemon::Dijkstra::run() "run()" or
823    ///\ref lemon::Dijkstra::start() "start()" must be called before
824    ///using them.
825
826    ///@{
827
828    ///The shortest path to a node.
829
830    ///Returns the shortest path to a node.
831    ///
832    ///\warning \c t should be reachable from the root(s).
833    ///
834    ///\pre Either \ref run() or \ref start() must be called before
835    ///using this function.
836    Path path(Node t) const { return Path(*G, *_pred, t); }
837
838    ///The distance of a node from the root(s).
839
840    ///Returns the distance of a node from the root(s).
841    ///
842    ///\warning If node \c v is not reachable from the root(s), then
843    ///the return value of this function is undefined.
844    ///
845    ///\pre Either \ref run() or \ref start() must be called before
846    ///using this function.
847    Value dist(Node v) const { return (*_dist)[v]; }
848
849    ///Returns the 'previous arc' of the shortest path tree for a node.
850
851    ///This function returns the 'previous arc' of the shortest path
852    ///tree for the node \c v, i.e. it returns the last arc of a
853    ///shortest path from the root(s) to \c v. It is \c INVALID if \c v
854    ///is not reachable from the root(s) or if \c v is a root.
855    ///
856    ///The shortest path tree used here is equal to the shortest path
857    ///tree used in \ref predNode().
858    ///
859    ///\pre Either \ref run() or \ref start() must be called before
860    ///using this function.
861    Arc predArc(Node v) const { return (*_pred)[v]; }
862
863    ///Returns the 'previous node' of the shortest path tree for a node.
864
865    ///This function returns the 'previous node' of the shortest path
866    ///tree for the node \c v, i.e. it returns the last but one node
867    ///from a shortest path from the root(s) to \c v. It is \c INVALID
868    ///if \c v is not reachable from the root(s) or if \c v is a root.
869    ///
870    ///The shortest path tree used here is equal to the shortest path
871    ///tree used in \ref predArc().
872    ///
873    ///\pre Either \ref run() or \ref start() must be called before
874    ///using this function.
875    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
876                                  G->source((*_pred)[v]); }
877
878    ///\brief Returns a const reference to the node map that stores the
879    ///distances of the nodes.
880    ///
881    ///Returns a const reference to the node map that stores the distances
882    ///of the nodes calculated by the algorithm.
883    ///
884    ///\pre Either \ref run() or \ref init()
885    ///must be called before using this function.
886    const DistMap &distMap() const { return *_dist;}
887
888    ///\brief Returns a const reference to the node map that stores the
889    ///predecessor arcs.
890    ///
891    ///Returns a const reference to the node map that stores the predecessor
892    ///arcs, which form the shortest path tree.
893    ///
894    ///\pre Either \ref run() or \ref init()
895    ///must be called before using this function.
896    const PredMap &predMap() const { return *_pred;}
897
898    ///Checks if a node is reachable from the root(s).
899
900    ///Returns \c true if \c v is reachable from the root(s).
901    ///\pre Either \ref run() or \ref start()
902    ///must be called before using this function.
903    bool reached(Node v) const { return (*_heap_cross_ref)[v] !=
904                                        Heap::PRE_HEAP; }
905
906    ///Checks if a node is processed.
907
908    ///Returns \c true if \c v is processed, i.e. the shortest
909    ///path to \c v has already found.
910    ///\pre Either \ref run() or \ref start()
911    ///must be called before using this function.
912    bool processed(Node v) const { return (*_heap_cross_ref)[v] ==
913                                          Heap::POST_HEAP; }
914
915    ///The current distance of a node from the root(s).
916
917    ///Returns the current distance of a node from the root(s).
918    ///It may be decreased in the following processes.
919    ///\pre \c v should be reached but not processed.
920    Value currentDist(Node v) const { return (*_heap)[v]; }
921
922    ///@}
923  };
924
925
926  ///Default traits class of dijkstra() function.
927
928  ///Default traits class of dijkstra() function.
929  ///\tparam GR The type of the digraph.
930  ///\tparam LM The type of the length map.
931  template<class GR, class LM>
932  struct DijkstraWizardDefaultTraits
933  {
934    ///The type of the digraph the algorithm runs on.
935    typedef GR Digraph;
936    ///The type of the map that stores the arc lengths.
937
938    ///The type of the map that stores the arc lengths.
939    ///It must meet the \ref concepts::ReadMap "ReadMap" concept.
940    typedef LM LengthMap;
941    ///The type of the length of the arcs.
942    typedef typename LM::Value Value;
943
944    /// Operation traits for Dijkstra algorithm.
945
946    /// This class defines the operations that are used in the algorithm.
947    /// \see DijkstraDefaultOperationTraits
948    typedef DijkstraDefaultOperationTraits<Value> OperationTraits;
949
950    /// The cross reference type used by the heap.
951
952    /// The cross reference type used by the heap.
953    /// Usually it is \c Digraph::NodeMap<int>.
954    typedef typename Digraph::template NodeMap<int> HeapCrossRef;
955    ///Instantiates a \ref HeapCrossRef.
956
957    ///This function instantiates a \ref HeapCrossRef.
958    /// \param g is the digraph, to which we would like to define the
959    /// HeapCrossRef.
960    /// \todo The digraph alone may be insufficient for the initialization
961    static HeapCrossRef *createHeapCrossRef(const Digraph &g)
962    {
963      return new HeapCrossRef(g);
964    }
965
966    ///The heap type used by the Dijkstra algorithm.
967
968    ///The heap type used by the Dijkstra algorithm.
969    ///
970    ///\sa BinHeap
971    ///\sa Dijkstra
972    typedef BinHeap<Value, typename Digraph::template NodeMap<int>,
973                    std::less<Value> > Heap;
974
975    ///Instantiates a \ref Heap.
976
977    ///This function instantiates a \ref Heap.
978    /// \param r is the HeapCrossRef which is used.
979    static Heap *createHeap(HeapCrossRef& r)
980    {
981      return new Heap(r);
982    }
983
984    ///\brief The type of the map that stores the predecessor
985    ///arcs of the shortest paths.
986    ///
987    ///The type of the map that stores the predecessor
988    ///arcs of the shortest paths.
989    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
990    typedef NullMap <typename Digraph::Node,typename Digraph::Arc> PredMap;
991    ///Instantiates a \ref PredMap.
992
993    ///This function instantiates a \ref PredMap.
994    ///\param g is the digraph, to which we would like to define the
995    ///\ref PredMap.
996    ///\todo The digraph alone may be insufficient to initialize
997#ifdef DOXYGEN
998    static PredMap *createPredMap(const Digraph &g)
999#else
1000    static PredMap *createPredMap(const Digraph &)
1001#endif
1002    {
1003      return new PredMap();
1004    }
1005
1006    ///The type of the map that indicates which nodes are processed.
1007
1008    ///The type of the map that indicates which nodes are processed.
1009    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
1010    ///By default it is a NullMap.
1011    ///\todo If it is set to a real map,
1012    ///Dijkstra::processed() should read this.
1013    ///\todo named parameter to set this type, function to read and write.
1014    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
1015    ///Instantiates a \ref ProcessedMap.
1016
1017    ///This function instantiates a \ref ProcessedMap.
1018    ///\param g is the digraph, to which
1019    ///we would like to define the \ref ProcessedMap.
1020#ifdef DOXYGEN
1021    static ProcessedMap *createProcessedMap(const Digraph &g)
1022#else
1023    static ProcessedMap *createProcessedMap(const Digraph &)
1024#endif
1025    {
1026      return new ProcessedMap();
1027    }
1028
1029    ///The type of the map that stores the distances of the nodes.
1030
1031    ///The type of the map that stores the distances of the nodes.
1032    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
1033    typedef NullMap<typename Digraph::Node,Value> DistMap;
1034    ///Instantiates a \ref DistMap.
1035
1036    ///This function instantiates a \ref DistMap.
1037    ///\param g is the digraph, to which we would like to define
1038    ///the \ref DistMap
1039#ifdef DOXYGEN
1040    static DistMap *createDistMap(const Digraph &g)
1041#else
1042    static DistMap *createDistMap(const Digraph &)
1043#endif
1044    {
1045      return new DistMap();
1046    }
1047  };
1048
1049  /// Default traits class used by \ref DijkstraWizard
1050
1051  /// To make it easier to use Dijkstra algorithm
1052  /// we have created a wizard class.
1053  /// This \ref DijkstraWizard class needs default traits,
1054  /// as well as the \ref Dijkstra class.
1055  /// The \ref DijkstraWizardBase is a class to be the default traits of the
1056  /// \ref DijkstraWizard class.
1057  /// \todo More named parameters are required...
1058  template<class GR,class LM>
1059  class DijkstraWizardBase : public DijkstraWizardDefaultTraits<GR,LM>
1060  {
1061    typedef DijkstraWizardDefaultTraits<GR,LM> Base;
1062  protected:
1063    //The type of the nodes in the digraph.
1064    typedef typename Base::Digraph::Node Node;
1065
1066    //Pointer to the digraph the algorithm runs on.
1067    void *_g;
1068    //Pointer to the length map
1069    void *_length;
1070    //Pointer to the map of predecessors arcs.
1071    void *_pred;
1072    //Pointer to the map of distances.
1073    void *_dist;
1074    //Pointer to the source node.
1075    Node _source;
1076
1077  public:
1078    /// Constructor.
1079
1080    /// This constructor does not require parameters, therefore it initiates
1081    /// all of the attributes to default values (0, INVALID).
1082    DijkstraWizardBase() : _g(0), _length(0), _pred(0),
1083                           _dist(0), _source(INVALID) {}
1084
1085    /// Constructor.
1086
1087    /// This constructor requires some parameters,
1088    /// listed in the parameters list.
1089    /// Others are initiated to 0.
1090    /// \param g The digraph the algorithm runs on.
1091    /// \param l The length map.
1092    /// \param s The source node.
1093    DijkstraWizardBase(const GR &g,const LM &l, Node s=INVALID) :
1094      _g(reinterpret_cast<void*>(const_cast<GR*>(&g))),
1095      _length(reinterpret_cast<void*>(const_cast<LM*>(&l))),
1096      _pred(0), _dist(0), _source(s) {}
1097
1098  };
1099
1100  /// Auxiliary class for the function type interface of Dijkstra algorithm.
1101
1102  /// This auxiliary class is created to implement the function type
1103  /// interface of \ref Dijkstra algorithm. It uses the functions and features
1104  /// of the plain \ref Dijkstra, but it is much simpler to use it.
1105  /// It should only be used through the \ref dijkstra() function, which makes
1106  /// it easier to use the algorithm.
1107  ///
1108  /// Simplicity means that the way to change the types defined
1109  /// in the traits class is based on functions that returns the new class
1110  /// and not on templatable built-in classes.
1111  /// When using the plain \ref Dijkstra
1112  /// the new class with the modified type comes from
1113  /// the original class by using the ::
1114  /// operator. In the case of \ref DijkstraWizard only
1115  /// a function have to be called, and it will
1116  /// return the needed class.
1117  ///
1118  /// It does not have own \ref run() method. When its \ref run() method
1119  /// is called, it initiates a plain \ref Dijkstra object, and calls the
1120  /// \ref Dijkstra::run() method of it.
1121  template<class TR>
1122  class DijkstraWizard : public TR
1123  {
1124    typedef TR Base;
1125
1126    ///The type of the digraph the algorithm runs on.
1127    typedef typename TR::Digraph Digraph;
1128
1129    typedef typename Digraph::Node Node;
1130    typedef typename Digraph::NodeIt NodeIt;
1131    typedef typename Digraph::Arc Arc;
1132    typedef typename Digraph::OutArcIt OutArcIt;
1133
1134    ///The type of the map that stores the arc lengths.
1135    typedef typename TR::LengthMap LengthMap;
1136    ///The type of the length of the arcs.
1137    typedef typename LengthMap::Value Value;
1138    ///\brief The type of the map that stores the predecessor
1139    ///arcs of the shortest paths.
1140    typedef typename TR::PredMap PredMap;
1141    ///The type of the map that stores the distances of the nodes.
1142    typedef typename TR::DistMap DistMap;
1143    ///The type of the map that indicates which nodes are processed.
1144    typedef typename TR::ProcessedMap ProcessedMap;
1145    ///The heap type used by the dijkstra algorithm.
1146    typedef typename TR::Heap Heap;
1147
1148  public:
1149
1150    /// Constructor.
1151    DijkstraWizard() : TR() {}
1152
1153    /// Constructor that requires parameters.
1154
1155    /// Constructor that requires parameters.
1156    /// These parameters will be the default values for the traits class.
1157    DijkstraWizard(const Digraph &g,const LengthMap &l, Node s=INVALID) :
1158      TR(g,l,s) {}
1159
1160    ///Copy constructor
1161    DijkstraWizard(const TR &b) : TR(b) {}
1162
1163    ~DijkstraWizard() {}
1164
1165    ///Runs Dijkstra algorithm from a source node.
1166
1167    ///Runs Dijkstra algorithm from a source node.
1168    ///The node can be given with the \ref source() function.
1169    void run()
1170    {
1171      if(Base::_source==INVALID) throw UninitializedParameter();
1172      Dijkstra<Digraph,LengthMap,TR>
1173        dij(*reinterpret_cast<const Digraph*>(Base::_g),
1174            *reinterpret_cast<const LengthMap*>(Base::_length));
1175      if(Base::_pred) dij.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
1176      if(Base::_dist) dij.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
1177      dij.run(Base::_source);
1178    }
1179
1180    ///Runs Dijkstra algorithm from the given node.
1181
1182    ///Runs Dijkstra algorithm from the given node.
1183    ///\param s is the given source.
1184    void run(Node s)
1185    {
1186      Base::_source=s;
1187      run();
1188    }
1189
1190    /// Sets the source node, from which the Dijkstra algorithm runs.
1191
1192    /// Sets the source node, from which the Dijkstra algorithm runs.
1193    /// \param s is the source node.
1194    DijkstraWizard<TR> &source(Node s)
1195    {
1196      Base::_source=s;
1197      return *this;
1198    }
1199
1200    template<class T>
1201    struct SetPredMapBase : public Base {
1202      typedef T PredMap;
1203      static PredMap *createPredMap(const Digraph &) { return 0; };
1204      SetPredMapBase(const TR &b) : TR(b) {}
1205    };
1206    ///\brief \ref named-templ-param "Named parameter"
1207    ///for setting \ref PredMap object.
1208    ///
1209    ///\ref named-templ-param "Named parameter"
1210    ///for setting \ref PredMap object.
1211    template<class T>
1212    DijkstraWizard<SetPredMapBase<T> > predMap(const T &t)
1213    {
1214      Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
1215      return DijkstraWizard<SetPredMapBase<T> >(*this);
1216    }
1217
1218    template<class T>
1219    struct SetProcessedMapBase : public Base {
1220      typedef T ProcessedMap;
1221      static ProcessedMap *createProcessedMap(const Digraph &) { return 0; };
1222      SetProcessedMapBase(const TR &b) : TR(b) {}
1223    };
1224    ///\brief \ref named-templ-param "Named parameter"
1225    ///for setting \ref ProcessedMap object.
1226    ///
1227    /// \ref named-templ-param "Named parameter"
1228    ///for setting \ref ProcessedMap object.
1229    template<class T>
1230    DijkstraWizard<SetProcessedMapBase<T> > processedMap(const T &t)
1231    {
1232      Base::_processed=reinterpret_cast<void*>(const_cast<T*>(&t));
1233      return DijkstraWizard<SetProcessedMapBase<T> >(*this);
1234    }
1235
1236    template<class T>
1237    struct SetDistMapBase : public Base {
1238      typedef T DistMap;
1239      static DistMap *createDistMap(const Digraph &) { return 0; };
1240      SetDistMapBase(const TR &b) : TR(b) {}
1241    };
1242    ///\brief \ref named-templ-param "Named parameter"
1243    ///for setting \ref DistMap object.
1244    ///
1245    ///\ref named-templ-param "Named parameter"
1246    ///for setting \ref DistMap object.
1247    template<class T>
1248    DijkstraWizard<SetDistMapBase<T> > distMap(const T &t)
1249    {
1250      Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
1251      return DijkstraWizard<SetDistMapBase<T> >(*this);
1252    }
1253
1254  };
1255
1256  ///Function type interface for Dijkstra algorithm.
1257
1258  /// \ingroup shortest_path
1259  ///Function type interface for Dijkstra algorithm.
1260  ///
1261  ///This function also has several
1262  ///\ref named-templ-func-param "named parameters",
1263  ///they are declared as the members of class \ref DijkstraWizard.
1264  ///The following
1265  ///example shows how to use these parameters.
1266  ///\code
1267  ///  dijkstra(g,length,source).predMap(preds).run();
1268  ///\endcode
1269  ///\warning Don't forget to put the \ref DijkstraWizard::run() "run()"
1270  ///to the end of the parameter list.
1271  ///\sa DijkstraWizard
1272  ///\sa Dijkstra
1273  template<class GR, class LM>
1274  DijkstraWizard<DijkstraWizardBase<GR,LM> >
1275  dijkstra(const GR &g,const LM &l,typename GR::Node s=INVALID)
1276  {
1277    return DijkstraWizard<DijkstraWizardBase<GR,LM> >(g,l,s);
1278  }
1279
1280} //END OF NAMESPACE LEMON
1281
1282#endif
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