COIN-OR::LEMON - Graph Library

source: lemon-1.0/lemon/dijkstra.h @ 208:4317d277ba21

Last change on this file since 208:4317d277ba21 was 184:716b220697a0, checked in by Alpar Juttner <alpar@…>, 12 years ago

Fix gcc-4.3 compilation errors and warnings

File size: 38.3 KB
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1/* -*- C++ -*-
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/bits/invalid.h>
31#include <lemon/error.h>
32#include <lemon/maps.h>
33
34namespace lemon {
35
36  /// \brief Default OperationTraits for the Dijkstra algorithm class.
37  /// 
38  /// It defines all computational operations and constants which are
39  /// 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 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 OperationTraits for the Dijkstra algorithm class.
57  /// 
58  /// It defines all computational operations and constants which are
59  /// used in the Dijkstra algorithm for widest path computation.
60  template <typename Value>
61  struct DijkstraWidestPathOperationTraits {
62    /// \brief Gives back the maximum value of the type.
63    static Value zero() {
64      return std::numeric_limits<Value>::max();
65    }
66    /// \brief Gives back the minimum of the given two elements.
67    static Value plus(const Value& left, const Value& right) {
68      return std::min(left, right);
69    }
70    /// \brief Gives back true only if the first value less than the second.
71    static bool less(const Value& left, const Value& right) {
72      return left < right;
73    }
74  };
75 
76  ///Default traits class of Dijkstra class.
77
78  ///Default traits class of Dijkstra class.
79  ///\tparam GR Digraph type.
80  ///\tparam LM Type of length map.
81  template<class GR, class LM>
82  struct DijkstraDefaultTraits
83  {
84    ///The digraph type the algorithm runs on.
85    typedef GR Digraph;
86    ///The type of the map that stores the arc lengths.
87
88    ///The type of the map that stores the arc lengths.
89    ///It must meet the \ref concepts::ReadMap "ReadMap" concept.
90    typedef LM LengthMap;
91    //The type of the length of the arcs.
92    typedef typename LM::Value Value;
93    /// Operation traits for Dijkstra algorithm.
94
95    /// It defines the used operation by the algorithm.
96    /// \see DijkstraDefaultOperationTraits
97    typedef DijkstraDefaultOperationTraits<Value> OperationTraits;
98    /// The cross reference type used by heap.
99
100
101    /// The cross reference type used by heap.
102    /// Usually it is \c Digraph::NodeMap<int>.
103    typedef typename Digraph::template NodeMap<int> HeapCrossRef;
104    ///Instantiates a HeapCrossRef.
105
106    ///This function instantiates a \c HeapCrossRef.
107    /// \param G is the digraph, to which we would like to define the
108    /// HeapCrossRef.
109    static HeapCrossRef *createHeapCrossRef(const GR &G)
110    {
111      return new HeapCrossRef(G);
112    }
113   
114    ///The heap type used by Dijkstra algorithm.
115
116    ///The heap type used by Dijkstra algorithm.
117    ///
118    ///\sa BinHeap
119    ///\sa Dijkstra
120    typedef BinHeap<typename LM::Value, HeapCrossRef, std::less<Value> > Heap;
121
122    static Heap *createHeap(HeapCrossRef& R)
123    {
124      return new Heap(R);
125    }
126
127    ///\brief The type of the map that stores the last
128    ///arcs of the shortest paths.
129    ///
130    ///The type of the map that stores the last
131    ///arcs of the shortest paths.
132    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
133    ///
134    typedef typename Digraph::template NodeMap<typename GR::Arc> PredMap;
135    ///Instantiates a PredMap.
136 
137    ///This function instantiates a \c PredMap.
138    ///\param G is the digraph, to which we would like to define the PredMap.
139    ///\todo The digraph alone may be insufficient for the initialization
140    static PredMap *createPredMap(const GR &G)
141    {
142      return new PredMap(G);
143    }
144
145    ///The type of the map that stores whether a nodes is processed.
146 
147    ///The type of the map that stores whether a nodes is processed.
148    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
149    ///By default it is a NullMap.
150    ///\todo If it is set to a real map,
151    ///Dijkstra::processed() should read this.
152    ///\todo named parameter to set this type, function to read and write.
153    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
154    ///Instantiates a ProcessedMap.
155 
156    ///This function instantiates a \c ProcessedMap.
157    ///\param g is the digraph, to which
158    ///we would like to define the \c ProcessedMap
159#ifdef DOXYGEN
160    static ProcessedMap *createProcessedMap(const GR &g)
161#else
162    static ProcessedMap *createProcessedMap(const GR &)
163#endif
164    {
165      return new ProcessedMap();
166    }
167    ///The type of the map that stores the dists of the nodes.
168 
169    ///The type of the map that stores the dists of the nodes.
170    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
171    ///
172    typedef typename Digraph::template NodeMap<typename LM::Value> DistMap;
173    ///Instantiates a DistMap.
174 
175    ///This function instantiates a \ref DistMap.
176    ///\param G is the digraph, to which we would like to define the \ref DistMap
177    static DistMap *createDistMap(const GR &G)
178    {
179      return new DistMap(G);
180    }
181  };
182 
183  ///%Dijkstra algorithm class.
184 
185  /// \ingroup shortest_path
186  ///This class provides an efficient implementation of %Dijkstra algorithm.
187  ///The arc lengths are passed to the algorithm using a
188  ///\ref concepts::ReadMap "ReadMap",
189  ///so it is easy to change it to any kind of length.
190  ///
191  ///The type of the length is determined by the
192  ///\ref concepts::ReadMap::Value "Value" of the length map.
193  ///
194  ///It is also possible to change the underlying priority heap.
195  ///
196  ///\tparam GR The digraph type the algorithm runs on. The default value
197  ///is \ref ListDigraph. The value of GR is not used directly by
198  ///Dijkstra, it is only passed to \ref DijkstraDefaultTraits.
199  ///\tparam LM This read-only ArcMap determines the lengths of the
200  ///arcs. It is read once for each arc, so the map may involve in
201  ///relatively time consuming process to compute the arc length if
202  ///it is necessary. The default map type is \ref
203  ///concepts::Digraph::ArcMap "Digraph::ArcMap<int>".  The value
204  ///of LM is not used directly by Dijkstra, it is only passed to \ref
205  ///DijkstraDefaultTraits. 
206  ///\tparam TR Traits class to set
207  ///various data types used by the algorithm.  The default traits
208  ///class is \ref DijkstraDefaultTraits
209  ///"DijkstraDefaultTraits<GR,LM>".  See \ref
210  ///DijkstraDefaultTraits for the documentation of a Dijkstra traits
211  ///class.
212
213#ifdef DOXYGEN
214  template <typename GR, typename LM, typename TR>
215#else
216  template <typename GR=ListDigraph,
217            typename LM=typename GR::template ArcMap<int>,
218            typename TR=DijkstraDefaultTraits<GR,LM> >
219#endif
220  class Dijkstra {
221  public:
222    /**
223     * \brief \ref Exception for uninitialized parameters.
224     *
225     * This error represents problems in the initialization
226     * of the parameters of the algorithms.
227     */
228    class UninitializedParameter : public lemon::UninitializedParameter {
229    public:
230      virtual const char* what() const throw() {
231        return "lemon::Dijkstra::UninitializedParameter";
232      }
233    };
234
235    typedef TR Traits;
236    ///The type of the underlying digraph.
237    typedef typename TR::Digraph Digraph;
238    ///\e
239    typedef typename Digraph::Node Node;
240    ///\e
241    typedef typename Digraph::NodeIt NodeIt;
242    ///\e
243    typedef typename Digraph::Arc Arc;
244    ///\e
245    typedef typename Digraph::OutArcIt OutArcIt;
246   
247    ///The type of the length of the arcs.
248    typedef typename TR::LengthMap::Value Value;
249    ///The type of the map that stores the arc lengths.
250    typedef typename TR::LengthMap LengthMap;
251    ///\brief The type of the map that stores the last
252    ///arcs of the shortest paths.
253    typedef typename TR::PredMap PredMap;
254    ///The type of the map indicating if a node is processed.
255    typedef typename TR::ProcessedMap ProcessedMap;
256    ///The type of the map that stores the dists of the nodes.
257    typedef typename TR::DistMap DistMap;
258    ///The cross reference type used for the current heap.
259    typedef typename TR::HeapCrossRef HeapCrossRef;
260    ///The heap type used by the dijkstra algorithm.
261    typedef typename TR::Heap Heap;
262    ///The operation traits.
263    typedef typename TR::OperationTraits OperationTraits;
264  private:
265    /// Pointer to the underlying digraph.
266    const Digraph *G;
267    /// Pointer to the length map
268    const LengthMap *length;
269    ///Pointer to the map of predecessors arcs.
270    PredMap *_pred;
271    ///Indicates if \ref _pred is locally allocated (\c true) or not.
272    bool local_pred;
273    ///Pointer to the map of distances.
274    DistMap *_dist;
275    ///Indicates if \ref _dist is locally allocated (\c true) or not.
276    bool local_dist;
277    ///Pointer to the map of processed status of the nodes.
278    ProcessedMap *_processed;
279    ///Indicates if \ref _processed is locally allocated (\c true) or not.
280    bool local_processed;
281    ///Pointer to the heap cross references.
282    HeapCrossRef *_heap_cross_ref;
283    ///Indicates if \ref _heap_cross_ref is locally allocated (\c true) or not.
284    bool local_heap_cross_ref;
285    ///Pointer to the heap.
286    Heap *_heap;
287    ///Indicates if \ref _heap is locally allocated (\c true) or not.
288    bool local_heap;
289
290    ///Creates the maps if necessary.
291   
292    ///\todo Better memory allocation (instead of new).
293    void create_maps()
294    {
295      if(!_pred) {
296        local_pred = true;
297        _pred = Traits::createPredMap(*G);
298      }
299      if(!_dist) {
300        local_dist = true;
301        _dist = Traits::createDistMap(*G);
302      }
303      if(!_processed) {
304        local_processed = true;
305        _processed = Traits::createProcessedMap(*G);
306      }
307      if (!_heap_cross_ref) {
308        local_heap_cross_ref = true;
309        _heap_cross_ref = Traits::createHeapCrossRef(*G);
310      }
311      if (!_heap) {
312        local_heap = true;
313        _heap = Traits::createHeap(*_heap_cross_ref);
314      }
315    }
316   
317  public :
318
319    typedef Dijkstra Create;
320 
321    ///\name Named template parameters
322
323    ///@{
324
325    template <class T>
326    struct DefPredMapTraits : public Traits {
327      typedef T PredMap;
328      static PredMap *createPredMap(const Digraph &)
329      {
330        throw UninitializedParameter();
331      }
332    };
333    ///\ref named-templ-param "Named parameter" for setting PredMap type
334
335    ///\ref named-templ-param "Named parameter" for setting PredMap type
336    ///
337    template <class T>
338    struct DefPredMap
339      : public Dijkstra< Digraph,       LengthMap, DefPredMapTraits<T> > {
340      typedef Dijkstra< Digraph,        LengthMap, DefPredMapTraits<T> > Create;
341    };
342   
343    template <class T>
344    struct DefDistMapTraits : public Traits {
345      typedef T DistMap;
346      static DistMap *createDistMap(const Digraph &)
347      {
348        throw UninitializedParameter();
349      }
350    };
351    ///\ref named-templ-param "Named parameter" for setting DistMap type
352
353    ///\ref named-templ-param "Named parameter" for setting DistMap type
354    ///
355    template <class T>
356    struct DefDistMap
357      : public Dijkstra< Digraph, LengthMap, DefDistMapTraits<T> > {
358      typedef Dijkstra< Digraph, LengthMap, DefDistMapTraits<T> > Create;
359    };
360   
361    template <class T>
362    struct DefProcessedMapTraits : public Traits {
363      typedef T ProcessedMap;
364      static ProcessedMap *createProcessedMap(const Digraph &G)
365      {
366        throw UninitializedParameter();
367      }
368    };
369    ///\ref named-templ-param "Named parameter" for setting ProcessedMap type
370
371    ///\ref named-templ-param "Named parameter" for setting ProcessedMap type
372    ///
373    template <class T>
374    struct DefProcessedMap
375      : public Dijkstra< Digraph,       LengthMap, DefProcessedMapTraits<T> > {
376      typedef Dijkstra< Digraph,        LengthMap, DefProcessedMapTraits<T> > Create;
377    };
378   
379    struct DefDigraphProcessedMapTraits : public Traits {
380      typedef typename Digraph::template NodeMap<bool> ProcessedMap;
381      static ProcessedMap *createProcessedMap(const Digraph &G)
382      {
383        return new ProcessedMap(G);
384      }
385    };
386    ///\brief \ref named-templ-param "Named parameter"
387    ///for setting the ProcessedMap type to be Digraph::NodeMap<bool>.
388    ///
389    ///\ref named-templ-param "Named parameter"
390    ///for setting the ProcessedMap type to be Digraph::NodeMap<bool>.
391    ///If you don't set it explicitely, it will be automatically allocated.
392    template <class T>
393    struct DefProcessedMapToBeDefaultMap
394      : public Dijkstra< Digraph, LengthMap, DefDigraphProcessedMapTraits> {
395      typedef Dijkstra< Digraph, LengthMap, DefDigraphProcessedMapTraits> Create;
396    };
397
398    template <class H, class CR>
399    struct DefHeapTraits : public Traits {
400      typedef CR HeapCrossRef;
401      typedef H Heap;
402      static HeapCrossRef *createHeapCrossRef(const Digraph &) {
403        throw UninitializedParameter();
404      }
405      static Heap *createHeap(HeapCrossRef &)
406      {
407        throw UninitializedParameter();
408      }
409    };
410    ///\brief \ref named-templ-param "Named parameter" for setting
411    ///heap and cross reference type
412    ///
413    ///\ref named-templ-param "Named parameter" for setting heap and cross
414    ///reference type
415    ///
416    template <class H, class CR = typename Digraph::template NodeMap<int> >
417    struct DefHeap
418      : public Dijkstra< Digraph,       LengthMap, DefHeapTraits<H, CR> > {
419      typedef Dijkstra< Digraph,        LengthMap, DefHeapTraits<H, CR> > Create;
420    };
421
422    template <class H, class CR>
423    struct DefStandardHeapTraits : public Traits {
424      typedef CR HeapCrossRef;
425      typedef H Heap;
426      static HeapCrossRef *createHeapCrossRef(const Digraph &G) {
427        return new HeapCrossRef(G);
428      }
429      static Heap *createHeap(HeapCrossRef &R)
430      {
431        return new Heap(R);
432      }
433    };
434    ///\brief \ref named-templ-param "Named parameter" for setting
435    ///heap and cross reference type with automatic allocation
436    ///
437    ///\ref named-templ-param "Named parameter" for setting heap and cross
438    ///reference type. It can allocate the heap and the cross reference
439    ///object if the cross reference's constructor waits for the digraph as
440    ///parameter and the heap's constructor waits for the cross reference.
441    template <class H, class CR = typename Digraph::template NodeMap<int> >
442    struct DefStandardHeap
443      : public Dijkstra< Digraph,       LengthMap, DefStandardHeapTraits<H, CR> > {
444      typedef Dijkstra< Digraph,        LengthMap, DefStandardHeapTraits<H, CR> >
445      Create;
446    };
447
448    template <class T>
449    struct DefOperationTraitsTraits : public Traits {
450      typedef T OperationTraits;
451    };
452   
453    /// \brief \ref named-templ-param "Named parameter" for setting
454    /// OperationTraits type
455    ///
456    /// \ref named-templ-param "Named parameter" for setting OperationTraits
457    /// type
458    template <class T>
459    struct DefOperationTraits
460      : public Dijkstra<Digraph, LengthMap, DefOperationTraitsTraits<T> > {
461      typedef Dijkstra<Digraph, LengthMap, DefOperationTraitsTraits<T> >
462      Create;
463    };
464   
465    ///@}
466
467
468  protected:
469
470    Dijkstra() {}
471
472  public:     
473   
474    ///Constructor.
475   
476    ///\param _G the digraph the algorithm will run on.
477    ///\param _length the length map used by the algorithm.
478    Dijkstra(const Digraph& _G, const LengthMap& _length) :
479      G(&_G), length(&_length),
480      _pred(NULL), local_pred(false),
481      _dist(NULL), local_dist(false),
482      _processed(NULL), local_processed(false),
483      _heap_cross_ref(NULL), local_heap_cross_ref(false),
484      _heap(NULL), local_heap(false)
485    { }
486   
487    ///Destructor.
488    ~Dijkstra()
489    {
490      if(local_pred) delete _pred;
491      if(local_dist) delete _dist;
492      if(local_processed) delete _processed;
493      if(local_heap_cross_ref) delete _heap_cross_ref;
494      if(local_heap) delete _heap;
495    }
496
497    ///Sets the length map.
498
499    ///Sets the length map.
500    ///\return <tt> (*this) </tt>
501    Dijkstra &lengthMap(const LengthMap &m)
502    {
503      length = &m;
504      return *this;
505    }
506
507    ///Sets the map storing the predecessor arcs.
508
509    ///Sets the map storing the predecessor arcs.
510    ///If you don't use this function before calling \ref run(),
511    ///it will allocate one. The destuctor deallocates this
512    ///automatically allocated map, of course.
513    ///\return <tt> (*this) </tt>
514    Dijkstra &predMap(PredMap &m)
515    {
516      if(local_pred) {
517        delete _pred;
518        local_pred=false;
519      }
520      _pred = &m;
521      return *this;
522    }
523
524    ///Sets the map storing the distances calculated by the algorithm.
525
526    ///Sets the map storing the distances calculated by the algorithm.
527    ///If you don't use this function before calling \ref run(),
528    ///it will allocate one. The destuctor deallocates this
529    ///automatically allocated map, of course.
530    ///\return <tt> (*this) </tt>
531    Dijkstra &distMap(DistMap &m)
532    {
533      if(local_dist) {
534        delete _dist;
535        local_dist=false;
536      }
537      _dist = &m;
538      return *this;
539    }
540
541    ///Sets the heap and the cross reference used by algorithm.
542
543    ///Sets the heap and the cross reference used by algorithm.
544    ///If you don't use this function before calling \ref run(),
545    ///it will allocate one. The destuctor deallocates this
546    ///automatically allocated heap and cross reference, of course.
547    ///\return <tt> (*this) </tt>
548    Dijkstra &heap(Heap& hp, HeapCrossRef &cr)
549    {
550      if(local_heap_cross_ref) {
551        delete _heap_cross_ref;
552        local_heap_cross_ref=false;
553      }
554      _heap_cross_ref = &cr;
555      if(local_heap) {
556        delete _heap;
557        local_heap=false;
558      }
559      _heap = &hp;
560      return *this;
561    }
562
563  private:
564    void finalizeNodeData(Node v,Value dst)
565    {
566      _processed->set(v,true);
567      _dist->set(v, dst);
568    }
569
570  public:
571
572    typedef PredMapPath<Digraph, PredMap> Path;
573
574    ///\name Execution control
575    ///The simplest way to execute the algorithm is to use
576    ///one of the member functions called \c run(...).
577    ///\n
578    ///If you need more control on the execution,
579    ///first you must call \ref init(), then you can add several source nodes
580    ///with \ref addSource().
581    ///Finally \ref start() will perform the actual path
582    ///computation.
583
584    ///@{
585
586    ///Initializes the internal data structures.
587
588    ///Initializes the internal data structures.
589    ///
590    void init()
591    {
592      create_maps();
593      _heap->clear();
594      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
595        _pred->set(u,INVALID);
596        _processed->set(u,false);
597        _heap_cross_ref->set(u,Heap::PRE_HEAP);
598      }
599    }
600   
601    ///Adds a new source node.
602
603    ///Adds a new source node to the priority heap.
604    ///
605    ///The optional second parameter is the initial distance of the node.
606    ///
607    ///It checks if the node has already been added to the heap and
608    ///it is pushed to the heap only if either it was not in the heap
609    ///or the shortest path found till then is shorter than \c dst.
610    void addSource(Node s,Value dst=OperationTraits::zero())
611    {
612      if(_heap->state(s) != Heap::IN_HEAP) {
613        _heap->push(s,dst);
614      } else if(OperationTraits::less((*_heap)[s], dst)) {
615        _heap->set(s,dst);
616        _pred->set(s,INVALID);
617      }
618    }
619   
620    ///Processes the next node in the priority heap
621
622    ///Processes the next node in the priority heap.
623    ///
624    ///\return The processed node.
625    ///
626    ///\warning The priority heap must not be empty!
627    Node processNextNode()
628    {
629      Node v=_heap->top();
630      Value oldvalue=_heap->prio();
631      _heap->pop();
632      finalizeNodeData(v,oldvalue);
633     
634      for(OutArcIt e(*G,v); e!=INVALID; ++e) {
635        Node w=G->target(e);
636        switch(_heap->state(w)) {
637        case Heap::PRE_HEAP:
638          _heap->push(w,OperationTraits::plus(oldvalue, (*length)[e]));
639          _pred->set(w,e);
640          break;
641        case Heap::IN_HEAP:
642          {
643            Value newvalue = OperationTraits::plus(oldvalue, (*length)[e]);
644            if ( OperationTraits::less(newvalue, (*_heap)[w]) ) {
645              _heap->decrease(w, newvalue);
646              _pred->set(w,e);
647            }
648          }
649          break;
650        case Heap::POST_HEAP:
651          break;
652        }
653      }
654      return v;
655    }
656
657    ///Next node to be processed.
658   
659    ///Next node to be processed.
660    ///
661    ///\return The next node to be processed or INVALID if the priority heap
662    /// is empty.
663    Node nextNode()
664    {
665      return !_heap->empty()?_heap->top():INVALID;
666    }
667 
668    ///\brief Returns \c false if there are nodes
669    ///to be processed in the priority heap
670    ///
671    ///Returns \c false if there are nodes
672    ///to be processed in the priority heap
673    bool emptyQueue() { return _heap->empty(); }
674    ///Returns the number of the nodes to be processed in the priority heap
675
676    ///Returns the number of the nodes to be processed in the priority heap
677    ///
678    int queueSize() { return _heap->size(); }
679   
680    ///Executes the algorithm.
681
682    ///Executes the algorithm.
683    ///
684    ///\pre init() must be called and at least one node should be added
685    ///with addSource() before using this function.
686    ///
687    ///This method runs the %Dijkstra algorithm from the root node(s)
688    ///in order to
689    ///compute the
690    ///shortest path to each node. The algorithm computes
691    ///- The shortest path tree.
692    ///- The distance of each node from the root(s).
693    ///
694    void start()
695    {
696      while ( !_heap->empty() ) processNextNode();
697    }
698   
699    ///Executes the algorithm until \c dest is reached.
700
701    ///Executes the algorithm until \c dest is reached.
702    ///
703    ///\pre init() must be called and at least one node should be added
704    ///with addSource() before using this function.
705    ///
706    ///This method runs the %Dijkstra algorithm from the root node(s)
707    ///in order to
708    ///compute the
709    ///shortest path to \c dest. The algorithm computes
710    ///- The shortest path to \c  dest.
711    ///- The distance of \c dest from the root(s).
712    ///
713    void start(Node dest)
714    {
715      while ( !_heap->empty() && _heap->top()!=dest ) processNextNode();
716      if ( !_heap->empty() ) finalizeNodeData(_heap->top(),_heap->prio());
717    }
718   
719    ///Executes the algorithm until a condition is met.
720
721    ///Executes the algorithm until a condition is met.
722    ///
723    ///\pre init() must be called and at least one node should be added
724    ///with addSource() before using this function.
725    ///
726    ///\param nm must be a bool (or convertible) node map. The algorithm
727    ///will stop when it reaches a node \c v with <tt>nm[v]</tt> true.
728    ///
729    ///\return The reached node \c v with <tt>nm[v]</tt> true or
730    ///\c INVALID if no such node was found.
731    template<class NodeBoolMap>
732    Node start(const NodeBoolMap &nm)
733    {
734      while ( !_heap->empty() && !nm[_heap->top()] ) processNextNode();
735      if ( _heap->empty() ) return INVALID;
736      finalizeNodeData(_heap->top(),_heap->prio());
737      return _heap->top();
738    }
739   
740    ///Runs %Dijkstra algorithm from node \c s.
741   
742    ///This method runs the %Dijkstra algorithm from a root node \c s
743    ///in order to
744    ///compute the
745    ///shortest path to each node. The algorithm computes
746    ///- The shortest path tree.
747    ///- The distance of each node from the root.
748    ///
749    ///\note d.run(s) is just a shortcut of the following code.
750    ///\code
751    ///  d.init();
752    ///  d.addSource(s);
753    ///  d.start();
754    ///\endcode
755    void run(Node s) {
756      init();
757      addSource(s);
758      start();
759    }
760   
761    ///Finds the shortest path between \c s and \c t.
762   
763    ///Finds the shortest path between \c s and \c t.
764    ///
765    ///\return The length of the shortest s---t path if there exists one,
766    ///0 otherwise.
767    ///\note Apart from the return value, d.run(s) is
768    ///just a shortcut of the following code.
769    ///\code
770    ///  d.init();
771    ///  d.addSource(s);
772    ///  d.start(t);
773    ///\endcode
774    Value run(Node s,Node t) {
775      init();
776      addSource(s);
777      start(t);
778      return (*_pred)[t]==INVALID?OperationTraits::zero():(*_dist)[t];
779    }
780   
781    ///@}
782
783    ///\name Query Functions
784    ///The result of the %Dijkstra algorithm can be obtained using these
785    ///functions.\n
786    ///Before the use of these functions,
787    ///either run() or start() must be called.
788   
789    ///@{
790
791    ///Gives back the shortest path.
792   
793    ///Gives back the shortest path.
794    ///\pre The \c t should be reachable from the source.
795    Path path(Node t)
796    {
797      return Path(*G, *_pred, t);
798    }
799
800    ///The distance of a node from the root.
801
802    ///Returns the distance of a node from the root.
803    ///\pre \ref run() must be called before using this function.
804    ///\warning If node \c v in unreachable from the root the return value
805    ///of this funcion is undefined.
806    Value dist(Node v) const { return (*_dist)[v]; }
807
808    ///The current distance of a node from the root.
809
810    ///Returns the current distance of a node from the root.
811    ///It may be decreased in the following processes.
812    ///\pre \c node should be reached but not processed
813    Value currentDist(Node v) const { return (*_heap)[v]; }
814
815    ///Returns the 'previous arc' of the shortest path tree.
816
817    ///For a node \c v it returns the 'previous arc' of the shortest path tree,
818    ///i.e. it returns the last arc of a shortest path from the root to \c
819    ///v. It is \ref INVALID
820    ///if \c v is unreachable from the root or if \c v=s. The
821    ///shortest path tree used here is equal to the shortest path tree used in
822    ///\ref predNode().  \pre \ref run() must be called before using
823    ///this function.
824    Arc predArc(Node v) const { return (*_pred)[v]; }
825
826    ///Returns the 'previous node' of the shortest path tree.
827
828    ///For a node \c v it returns the 'previous node' of the shortest path tree,
829    ///i.e. it returns the last but one node from a shortest path from the
830    ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
831    ///\c v=s. The shortest path tree used here is equal to the shortest path
832    ///tree used in \ref predArc().  \pre \ref run() must be called before
833    ///using this function.
834    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
835                                  G->source((*_pred)[v]); }
836   
837    ///Returns a reference to the NodeMap of distances.
838
839    ///Returns a reference to the NodeMap of distances. \pre \ref run() must
840    ///be called before using this function.
841    const DistMap &distMap() const { return *_dist;}
842 
843    ///Returns a reference to the shortest path tree map.
844
845    ///Returns a reference to the NodeMap of the arcs of the
846    ///shortest path tree.
847    ///\pre \ref run() must be called before using this function.
848    const PredMap &predMap() const { return *_pred;}
849 
850    ///Checks if a node is reachable from the root.
851
852    ///Returns \c true if \c v is reachable from the root.
853    ///\warning The source nodes are inditated as unreached.
854    ///\pre \ref run() must be called before using this function.
855    ///
856    bool reached(Node v) { return (*_heap_cross_ref)[v] != Heap::PRE_HEAP; }
857
858    ///Checks if a node is processed.
859
860    ///Returns \c true if \c v is processed, i.e. the shortest
861    ///path to \c v has already found.
862    ///\pre \ref run() must be called before using this function.
863    ///
864    bool processed(Node v) { return (*_heap_cross_ref)[v] == Heap::POST_HEAP; }
865   
866    ///@}
867  };
868
869
870
871
872 
873  ///Default traits class of Dijkstra function.
874
875  ///Default traits class of Dijkstra function.
876  ///\tparam GR Digraph type.
877  ///\tparam LM Type of length map.
878  template<class GR, class LM>
879  struct DijkstraWizardDefaultTraits
880  {
881    ///The digraph type the algorithm runs on.
882    typedef GR Digraph;
883    ///The type of the map that stores the arc lengths.
884
885    ///The type of the map that stores the arc lengths.
886    ///It must meet the \ref concepts::ReadMap "ReadMap" concept.
887    typedef LM LengthMap;
888    //The type of the length of the arcs.
889    typedef typename LM::Value Value;
890    /// Operation traits for Dijkstra algorithm.
891
892    /// It defines the used operation by the algorithm.
893    /// \see DijkstraDefaultOperationTraits
894    typedef DijkstraDefaultOperationTraits<Value> OperationTraits;
895    ///The heap type used by Dijkstra algorithm.
896
897    /// The cross reference type used by heap.
898
899    /// The cross reference type used by heap.
900    /// Usually it is \c Digraph::NodeMap<int>.
901    typedef typename Digraph::template NodeMap<int> HeapCrossRef;
902    ///Instantiates a HeapCrossRef.
903
904    ///This function instantiates a \ref HeapCrossRef.
905    /// \param G is the digraph, to which we would like to define the
906    /// HeapCrossRef.
907    /// \todo The digraph alone may be insufficient for the initialization
908    static HeapCrossRef *createHeapCrossRef(const GR &G)
909    {
910      return new HeapCrossRef(G);
911    }
912   
913    ///The heap type used by Dijkstra algorithm.
914
915    ///The heap type used by Dijkstra algorithm.
916    ///
917    ///\sa BinHeap
918    ///\sa Dijkstra
919    typedef BinHeap<typename LM::Value, typename GR::template NodeMap<int>,
920                    std::less<Value> > Heap;
921
922    static Heap *createHeap(HeapCrossRef& R)
923    {
924      return new Heap(R);
925    }
926
927    ///\brief The type of the map that stores the last
928    ///arcs of the shortest paths.
929    ///
930    ///The type of the map that stores the last
931    ///arcs of the shortest paths.
932    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
933    ///
934    typedef NullMap <typename GR::Node,typename GR::Arc> PredMap;
935    ///Instantiates a PredMap.
936 
937    ///This function instantiates a \ref PredMap.
938    ///\param g is the digraph, to which we would like to define the PredMap.
939    ///\todo The digraph alone may be insufficient for the initialization
940#ifdef DOXYGEN
941    static PredMap *createPredMap(const GR &g)
942#else
943    static PredMap *createPredMap(const GR &)
944#endif
945    {
946      return new PredMap();
947    }
948    ///The type of the map that stores whether a nodes is processed.
949 
950    ///The type of the map that stores whether a nodes is processed.
951    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
952    ///By default it is a NullMap.
953    ///\todo If it is set to a real map,
954    ///Dijkstra::processed() should read this.
955    ///\todo named parameter to set this type, function to read and write.
956    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
957    ///Instantiates a ProcessedMap.
958 
959    ///This function instantiates a \ref ProcessedMap.
960    ///\param g is the digraph, to which
961    ///we would like to define the \ref ProcessedMap
962#ifdef DOXYGEN
963    static ProcessedMap *createProcessedMap(const GR &g)
964#else
965    static ProcessedMap *createProcessedMap(const GR &)
966#endif
967    {
968      return new ProcessedMap();
969    }
970    ///The type of the map that stores the dists of the nodes.
971 
972    ///The type of the map that stores the dists of the nodes.
973    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
974    ///
975    typedef NullMap<typename Digraph::Node,typename LM::Value> DistMap;
976    ///Instantiates a DistMap.
977 
978    ///This function instantiates a \ref DistMap.
979    ///\param g is the digraph, to which we would like to define the \ref DistMap
980#ifdef DOXYGEN
981    static DistMap *createDistMap(const GR &g)
982#else
983    static DistMap *createDistMap(const GR &)
984#endif
985    {
986      return new DistMap();
987    }
988  };
989 
990  /// Default traits used by \ref DijkstraWizard
991
992  /// To make it easier to use Dijkstra algorithm
993  ///we have created a wizard class.
994  /// This \ref DijkstraWizard class needs default traits,
995  ///as well as the \ref Dijkstra class.
996  /// The \ref DijkstraWizardBase is a class to be the default traits of the
997  /// \ref DijkstraWizard class.
998  /// \todo More named parameters are required...
999  template<class GR,class LM>
1000  class DijkstraWizardBase : public DijkstraWizardDefaultTraits<GR,LM>
1001  {
1002
1003    typedef DijkstraWizardDefaultTraits<GR,LM> Base;
1004  protected:
1005    /// Type of the nodes in the digraph.
1006    typedef typename Base::Digraph::Node Node;
1007
1008    /// Pointer to the underlying digraph.
1009    void *_g;
1010    /// Pointer to the length map
1011    void *_length;
1012    ///Pointer to the map of predecessors arcs.
1013    void *_pred;
1014    ///Pointer to the map of distances.
1015    void *_dist;
1016    ///Pointer to the source node.
1017    Node _source;
1018
1019    public:
1020    /// Constructor.
1021   
1022    /// This constructor does not require parameters, therefore it initiates
1023    /// all of the attributes to default values (0, INVALID).
1024    DijkstraWizardBase() : _g(0), _length(0), _pred(0),
1025                           _dist(0), _source(INVALID) {}
1026
1027    /// Constructor.
1028   
1029    /// This constructor requires some parameters,
1030    /// listed in the parameters list.
1031    /// Others are initiated to 0.
1032    /// \param g is the initial value of  \ref _g
1033    /// \param l is the initial value of  \ref _length
1034    /// \param s is the initial value of  \ref _source
1035    DijkstraWizardBase(const GR &g,const LM &l, Node s=INVALID) :
1036      _g(reinterpret_cast<void*>(const_cast<GR*>(&g))),
1037      _length(reinterpret_cast<void*>(const_cast<LM*>(&l))),
1038      _pred(0), _dist(0), _source(s) {}
1039
1040  };
1041 
1042  /// A class to make the usage of Dijkstra algorithm easier
1043
1044  /// This class is created to make it easier to use Dijkstra algorithm.
1045  /// It uses the functions and features of the plain \ref Dijkstra,
1046  /// but it is much simpler to use it.
1047  ///
1048  /// Simplicity means that the way to change the types defined
1049  /// in the traits class is based on functions that returns the new class
1050  /// and not on templatable built-in classes.
1051  /// When using the plain \ref Dijkstra
1052  /// the new class with the modified type comes from
1053  /// the original class by using the ::
1054  /// operator. In the case of \ref DijkstraWizard only
1055  /// a function have to be called and it will
1056  /// return the needed class.
1057  ///
1058  /// It does not have own \ref run method. When its \ref run method is called
1059  /// it initiates a plain \ref Dijkstra class, and calls the \ref
1060  /// Dijkstra::run method of it.
1061  template<class TR>
1062  class DijkstraWizard : public TR
1063  {
1064    typedef TR Base;
1065
1066    ///The type of the underlying digraph.
1067    typedef typename TR::Digraph Digraph;
1068    //\e
1069    typedef typename Digraph::Node Node;
1070    //\e
1071    typedef typename Digraph::NodeIt NodeIt;
1072    //\e
1073    typedef typename Digraph::Arc Arc;
1074    //\e
1075    typedef typename Digraph::OutArcIt OutArcIt;
1076   
1077    ///The type of the map that stores the arc lengths.
1078    typedef typename TR::LengthMap LengthMap;
1079    ///The type of the length of the arcs.
1080    typedef typename LengthMap::Value Value;
1081    ///\brief The type of the map that stores the last
1082    ///arcs of the shortest paths.
1083    typedef typename TR::PredMap PredMap;
1084    ///The type of the map that stores the dists of the nodes.
1085    typedef typename TR::DistMap DistMap;
1086    ///The heap type used by the dijkstra algorithm.
1087    typedef typename TR::Heap Heap;
1088  public:
1089    /// Constructor.
1090    DijkstraWizard() : TR() {}
1091
1092    /// Constructor that requires parameters.
1093
1094    /// Constructor that requires parameters.
1095    /// These parameters will be the default values for the traits class.
1096    DijkstraWizard(const Digraph &g,const LengthMap &l, Node s=INVALID) :
1097      TR(g,l,s) {}
1098
1099    ///Copy constructor
1100    DijkstraWizard(const TR &b) : TR(b) {}
1101
1102    ~DijkstraWizard() {}
1103
1104    ///Runs Dijkstra algorithm from a given node.
1105   
1106    ///Runs Dijkstra algorithm from a given node.
1107    ///The node can be given by the \ref source function.
1108    void run()
1109    {
1110      if(Base::_source==INVALID) throw UninitializedParameter();
1111      Dijkstra<Digraph,LengthMap,TR>
1112        dij(*reinterpret_cast<const Digraph*>(Base::_g),
1113            *reinterpret_cast<const LengthMap*>(Base::_length));
1114      if(Base::_pred) dij.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
1115      if(Base::_dist) dij.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
1116      dij.run(Base::_source);
1117    }
1118
1119    ///Runs Dijkstra algorithm from the given node.
1120
1121    ///Runs Dijkstra algorithm from the given node.
1122    ///\param s is the given source.
1123    void run(Node s)
1124    {
1125      Base::_source=s;
1126      run();
1127    }
1128
1129    template<class T>
1130    struct DefPredMapBase : public Base {
1131      typedef T PredMap;
1132      static PredMap *createPredMap(const Digraph &) { return 0; };
1133      DefPredMapBase(const TR &b) : TR(b) {}
1134    };
1135   
1136    ///\brief \ref named-templ-param "Named parameter"
1137    ///function for setting PredMap type
1138    ///
1139    /// \ref named-templ-param "Named parameter"
1140    ///function for setting PredMap type
1141    ///
1142    template<class T>
1143    DijkstraWizard<DefPredMapBase<T> > predMap(const T &t)
1144    {
1145      Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
1146      return DijkstraWizard<DefPredMapBase<T> >(*this);
1147    }
1148   
1149    template<class T>
1150    struct DefDistMapBase : public Base {
1151      typedef T DistMap;
1152      static DistMap *createDistMap(const Digraph &) { return 0; };
1153      DefDistMapBase(const TR &b) : TR(b) {}
1154    };
1155   
1156    ///\brief \ref named-templ-param "Named parameter"
1157    ///function for setting DistMap type
1158    ///
1159    /// \ref named-templ-param "Named parameter"
1160    ///function for setting DistMap type
1161    ///
1162    template<class T>
1163    DijkstraWizard<DefDistMapBase<T> > distMap(const T &t)
1164    {
1165      Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
1166      return DijkstraWizard<DefDistMapBase<T> >(*this);
1167    }
1168   
1169    /// Sets the source node, from which the Dijkstra algorithm runs.
1170
1171    /// Sets the source node, from which the Dijkstra algorithm runs.
1172    /// \param s is the source node.
1173    DijkstraWizard<TR> &source(Node s)
1174    {
1175      Base::_source=s;
1176      return *this;
1177    }
1178   
1179  };
1180 
1181  ///Function type interface for Dijkstra algorithm.
1182
1183  /// \ingroup shortest_path
1184  ///Function type interface for Dijkstra algorithm.
1185  ///
1186  ///This function also has several
1187  ///\ref named-templ-func-param "named parameters",
1188  ///they are declared as the members of class \ref DijkstraWizard.
1189  ///The following
1190  ///example shows how to use these parameters.
1191  ///\code
1192  ///  dijkstra(g,length,source).predMap(preds).run();
1193  ///\endcode
1194  ///\warning Don't forget to put the \ref DijkstraWizard::run() "run()"
1195  ///to the end of the parameter list.
1196  ///\sa DijkstraWizard
1197  ///\sa Dijkstra
1198  template<class GR, class LM>
1199  DijkstraWizard<DijkstraWizardBase<GR,LM> >
1200  dijkstra(const GR &g,const LM &l,typename GR::Node s=INVALID)
1201  {
1202    return DijkstraWizard<DijkstraWizardBase<GR,LM> >(g,l,s);
1203  }
1204
1205} //END OF NAMESPACE LEMON
1206
1207#endif
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