COIN-OR::LEMON - Graph Library

source: lemon-0.x/src/work/alpar/dijkstra.h @ 1117:5767cc417f62

Last change on this file since 1117:5767cc417f62 was 1117:5767cc417f62, checked in by Alpar Juttner, 15 years ago

Bugfix

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1/* -*- C++ -*-
2 * src/lemon/dijkstra.h - Part of LEMON, a generic C++ optimization library
3 *
4 * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
5 * (Egervary Combinatorial Optimization Research Group, 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_DIJKSTRA_H
18#define LEMON_DIJKSTRA_H
19
20///\ingroup flowalgs
21///\file
22///\brief Dijkstra algorithm.
23
24#include <lemon/list_graph.h>
25#include <lemon/bin_heap.h>
26#include <lemon/invalid.h>
27
28namespace lemon {
29
30/// \addtogroup flowalgs
31/// @{
32
33  ///Default traits class of Dijkstra class.
34
35  ///Default traits class of Dijkstra class.
36  ///\param GR Graph type.
37  ///\param LM Type of length map.
38  template<class GR, class LM>
39  struct DijkstraDefaultTraits
40  {
41    ///The graph type the algorithm runs on.
42    typedef GR Graph;
43    ///The type of the map that stores the edge lengths.
44
45    ///It must meet the \ref concept::ReadMap "ReadMap" concept.
46    ///
47    typedef LM LengthMap;
48    //The type of the length of the edges.
49    typedef typename LM::Value Value;
50    ///The heap type used by Dijkstra algorithm.
51
52    ///The heap type used by Dijkstra algorithm.
53    ///
54    ///\sa BinHeap
55    ///\sa Dijkstra
56    typedef BinHeap<typename Graph::Node,
57                    typename LM::Value,
58                    typename GR::template NodeMap<int>,
59                    std::less<Value> > Heap;
60
61    ///\brief The type of the map that stores the last
62    ///edges of the shortest paths.
63    ///
64    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
65    ///
66    typedef typename Graph::template NodeMap<typename GR::Edge> PredMap;
67    ///Instantiates a PredMap.
68 
69    ///\todo Please document...
70    ///
71    static PredMap *createPredMap(const GR &G)
72    {
73      return new PredMap(G);
74    }
75    ///\brief The type of the map that stores the last but one
76    ///nodes of the shortest paths.
77    ///
78    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
79    ///
80    typedef typename Graph::template NodeMap<typename GR::Node> PredNodeMap;
81    ///Instantiates a PredNodeMap.
82 
83    ///\todo Please document...
84    ///
85    static PredNodeMap *createPredNodeMap(const GR &G)
86    {
87      return new PredNodeMap(G);
88    }
89    ///The type of the map that stores the dists of the nodes.
90 
91    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
92    ///
93    typedef typename Graph::template NodeMap<typename LM::Value> DistMap;
94    ///Instantiates a DistMap.
95 
96    ///\todo Please document...
97    ///
98    static DistMap *createDistMap(const GR &G)
99    {
100      return new DistMap(G);
101    }
102  };
103 
104  ///%Dijkstra algorithm class.
105
106  ///This class provides an efficient implementation of %Dijkstra algorithm.
107  ///The edge lengths are passed to the algorithm using a
108  ///\ref concept::ReadMap "ReadMap",
109  ///so it is easy to change it to any kind of length.
110  ///
111  ///The type of the length is determined by the
112  ///\ref concept::ReadMap::Value "Value" of the length map.
113  ///
114  ///It is also possible to change the underlying priority heap.
115  ///
116  ///\param GR The graph type the algorithm runs on. The default value is
117  ///\ref ListGraph. The value of GR is not used directly by Dijkstra, it
118  ///is only passed to \ref DijkstraDefaultTraits.
119  ///\param LM This read-only
120  ///EdgeMap
121  ///determines the
122  ///lengths of the edges. It is read once for each edge, so the map
123  ///may involve in relatively time consuming process to compute the edge
124  ///length if it is necessary. The default map type is
125  ///\ref concept::StaticGraph::EdgeMap "Graph::EdgeMap<int>".
126  ///The value of LM is not used directly by Dijkstra, it
127  ///is only passed to \ref DijkstraDefaultTraits.
128  ///\param TR Traits class to set various data types used by the algorithm.
129  ///The default traits class is
130  ///\ref DijkstraDefaultTraits "DijkstraDefaultTraits<GR,LM>".
131  ///See \ref DijkstraDefaultTraits for the documentation of
132  ///a Dijkstra traits class.
133  ///
134  ///\author Jacint Szabo and Alpar Juttner
135  ///\todo We need a typedef-names should be standardized. (-:
136
137#ifdef DOXYGEN
138  template <typename GR,
139            typename LM,
140            typename TR>
141#else
142  template <typename GR=ListGraph,
143            typename LM=typename GR::template EdgeMap<int>,
144            typename TR=DijkstraDefaultTraits<GR,LM> >
145#endif
146  class Dijkstra {
147  public:
148    typedef TR Traits;
149    ///The type of the underlying graph.
150    typedef typename TR::Graph Graph;
151    ///\e
152    typedef typename Graph::Node Node;
153    ///\e
154    typedef typename Graph::NodeIt NodeIt;
155    ///\e
156    typedef typename Graph::Edge Edge;
157    ///\e
158    typedef typename Graph::OutEdgeIt OutEdgeIt;
159   
160    ///The type of the length of the edges.
161    typedef typename TR::LengthMap::Value Value;
162    ///The type of the map that stores the edge lengths.
163    typedef typename TR::LengthMap LengthMap;
164    ///\brief The type of the map that stores the last
165    ///edges of the shortest paths.
166    typedef typename TR::PredMap PredMap;
167    ///\brief The type of the map that stores the last but one
168    ///nodes of the shortest paths.
169    typedef typename TR::PredNodeMap PredNodeMap;
170    ///The type of the map that stores the dists of the nodes.
171    typedef typename TR::DistMap DistMap;
172    ///The heap type used by the dijkstra algorithm.
173    typedef typename TR::Heap Heap;
174  private:
175    /// Pointer to the underlying graph.
176    const Graph *G;
177    /// Pointer to the length map
178    const LengthMap *length;
179    ///Pointer to the map of predecessors edges.
180    PredMap *predecessor;
181    ///Indicates if \ref predecessor is locally allocated (\c true) or not.
182    bool local_predecessor;
183    ///Pointer to the map of predecessors nodes.
184    PredNodeMap *pred_node;
185    ///Indicates if \ref pred_node is locally allocated (\c true) or not.
186    bool local_pred_node;
187    ///Pointer to the map of distances.
188    DistMap *distance;
189    ///Indicates if \ref distance is locally allocated (\c true) or not.
190    bool local_distance;
191
192    ///The source node of the last execution.
193    Node source;
194
195    ///Initializes the maps.
196   
197    ///\todo Error if \c G or are \c NULL. What about \c length?
198    ///\todo Better memory allocation (instead of new).
199    void init_maps()
200    {
201      if(!predecessor) {
202        local_predecessor = true;
203        predecessor = Traits::createPredMap(*G);
204      }
205      if(!pred_node) {
206        local_pred_node = true;
207        pred_node = Traits::createPredNodeMap(*G);
208      }
209      if(!distance) {
210        local_distance = true;
211        distance = Traits::createDistMap(*G);
212      }
213    }
214   
215  public :
216 
217    template <class T>
218    struct DefPredMapTraits : public Traits {
219      typedef T PredMap;
220      ///\todo An exception should be thrown.
221      ///
222      static PredMap *createPredMap(const Graph &G)
223      {
224        std::cerr << __FILE__ ":" << __LINE__ <<
225          ": error: Special maps should be manually created" << std::endl;
226        exit(1);
227      }
228    };
229    ///\ref named-templ-param "Named parameter" for setting PredMap type
230
231    ///\ref named-templ-param "Named parameter" for setting PredMap type
232    ///
233    template <class T>
234    class DefPredMap : public Dijkstra< Graph,
235                                        LengthMap,
236                                        DefPredMapTraits<T> > { };
237   
238    template <class T>
239    struct DefPredNodeMapTraits : public Traits {
240      typedef T PredNodeMap;
241      ///\todo An exception should be thrown.
242      ///
243      static PredNodeMap *createPredNodeMap(const Graph &G)
244      {
245        std::cerr << __FILE__ ":" << __LINE__ <<
246          ": error: Special maps should be manually created" << std::endl;
247        exit(1);
248      }
249    };
250    ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
251
252    ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
253    ///
254    template <class T>
255    class DefPredNodeMap : public Dijkstra< Graph,
256                                            LengthMap,
257                                            DefPredNodeMapTraits<T> > { };
258   
259    template <class T>
260    struct DefDistMapTraits : public Traits {
261      typedef T DistMap;
262      ///\todo An exception should be thrown.
263      ///
264      static DistMap *createDistMap(const Graph &G)
265      {
266        std::cerr << __FILE__ ":" << __LINE__ <<
267          ": error: Special maps should be manually created" << std::endl;
268        exit(1);
269      }
270    };
271    ///\ref named-templ-param "Named parameter" for setting DistMap type
272
273    ///\ref named-templ-param "Named parameter" for setting DistMap type
274    ///
275    template <class T>
276    class DefDistMap : public Dijkstra< Graph,
277                                        LengthMap,
278                                        DefDistMapTraits<T> > { };
279   
280    ///Constructor.
281   
282    ///\param _G the graph the algorithm will run on.
283    ///\param _length the length map used by the algorithm.
284    Dijkstra(const Graph& _G, const LengthMap& _length) :
285      G(&_G), length(&_length),
286      predecessor(NULL), local_predecessor(false),
287      pred_node(NULL), local_pred_node(false),
288      distance(NULL), local_distance(false)
289    { }
290   
291    ///Destructor.
292    ~Dijkstra()
293    {
294      if(local_predecessor) delete predecessor;
295      if(local_pred_node) delete pred_node;
296      if(local_distance) delete distance;
297    }
298
299    ///Sets the length map.
300
301    ///Sets the length map.
302    ///\return <tt> (*this) </tt>
303    Dijkstra &lengthMap(const LengthMap &m)
304    {
305      length = &m;
306      return *this;
307    }
308
309    ///Sets the map storing the predecessor edges.
310
311    ///Sets the map storing the predecessor edges.
312    ///If you don't use this function before calling \ref run(),
313    ///it will allocate one. The destuctor deallocates this
314    ///automatically allocated map, of course.
315    ///\return <tt> (*this) </tt>
316    Dijkstra &predMap(PredMap &m)
317    {
318      if(local_predecessor) {
319        delete predecessor;
320        local_predecessor=false;
321      }
322      predecessor = &m;
323      return *this;
324    }
325
326    ///Sets the map storing the predecessor nodes.
327
328    ///Sets the map storing the predecessor nodes.
329    ///If you don't use this function before calling \ref run(),
330    ///it will allocate one. The destuctor deallocates this
331    ///automatically allocated map, of course.
332    ///\return <tt> (*this) </tt>
333    Dijkstra &predNodeMap(PredNodeMap &m)
334    {
335      if(local_pred_node) {
336        delete pred_node;
337        local_pred_node=false;
338      }
339      pred_node = &m;
340      return *this;
341    }
342
343    ///Sets the map storing the distances calculated by the algorithm.
344
345    ///Sets the map storing the distances calculated by the algorithm.
346    ///If you don't use this function before calling \ref run(),
347    ///it will allocate one. The destuctor deallocates this
348    ///automatically allocated map, of course.
349    ///\return <tt> (*this) </tt>
350    Dijkstra &distMap(DistMap &m)
351    {
352      if(local_distance) {
353        delete distance;
354        local_distance=false;
355      }
356      distance = &m;
357      return *this;
358    }
359   
360  ///Runs %Dijkstra algorithm from node \c s.
361
362  ///This method runs the %Dijkstra algorithm from a root node \c s
363  ///in order to
364  ///compute the
365  ///shortest path to each node. The algorithm computes
366  ///- The shortest path tree.
367  ///- The distance of each node from the root.
368  ///\todo heap_map's type could also be in the traits class.
369    void run(Node s) {
370     
371      init_maps();
372     
373      source = s;
374     
375      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
376        predecessor->set(u,INVALID);
377        pred_node->set(u,INVALID);
378      }
379     
380      typename Graph::template NodeMap<int> heap_map(*G,-1);
381     
382      Heap heap(heap_map);
383     
384      heap.push(s,0);
385     
386      while ( !heap.empty() ) {
387       
388        Node v=heap.top();
389        Value oldvalue=heap[v];
390        heap.pop();
391        distance->set(v, oldvalue);
392       
393       
394        for(OutEdgeIt e(*G,v); e!=INVALID; ++e) {
395          Node w=G->target(e);
396          switch(heap.state(w)) {
397          case Heap::PRE_HEAP:
398            heap.push(w,oldvalue+(*length)[e]);
399            predecessor->set(w,e);
400            pred_node->set(w,v);
401            break;
402          case Heap::IN_HEAP:
403            if ( oldvalue+(*length)[e] < heap[w] ) {
404              heap.decrease(w, oldvalue+(*length)[e]);
405              predecessor->set(w,e);
406              pred_node->set(w,v);
407            }
408            break;
409          case Heap::POST_HEAP:
410            break;
411          }
412        }
413      }
414    }
415   
416    ///The distance of a node from the root.
417
418    ///Returns the distance of a node from the root.
419    ///\pre \ref run() must be called before using this function.
420    ///\warning If node \c v in unreachable from the root the return value
421    ///of this funcion is undefined.
422    Value dist(Node v) const { return (*distance)[v]; }
423
424    ///Returns the 'previous edge' of the shortest path tree.
425
426    ///For a node \c v it returns the 'previous edge' of the shortest path tree,
427    ///i.e. it returns the last edge of a shortest path from the root to \c
428    ///v. It is \ref INVALID
429    ///if \c v is unreachable from the root or if \c v=s. The
430    ///shortest path tree used here is equal to the shortest path tree used in
431    ///\ref predNode(Node v).  \pre \ref run() must be called before using
432    ///this function.
433    ///\todo predEdge could be a better name.
434    Edge pred(Node v) const { return (*predecessor)[v]; }
435
436    ///Returns the 'previous node' of the shortest path tree.
437
438    ///For a node \c v it returns the 'previous node' of the shortest path tree,
439    ///i.e. it returns the last but one node from a shortest path from the
440    ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
441    ///\c v=s. The shortest path tree used here is equal to the shortest path
442    ///tree used in \ref pred(Node v).  \pre \ref run() must be called before
443    ///using this function.
444    Node predNode(Node v) const { return (*pred_node)[v]; }
445   
446    ///Returns a reference to the NodeMap of distances.
447
448    ///Returns a reference to the NodeMap of distances. \pre \ref run() must
449    ///be called before using this function.
450    const DistMap &distMap() const { return *distance;}
451 
452    ///Returns a reference to the shortest path tree map.
453
454    ///Returns a reference to the NodeMap of the edges of the
455    ///shortest path tree.
456    ///\pre \ref run() must be called before using this function.
457    const PredMap &predMap() const { return *predecessor;}
458 
459    ///Returns a reference to the map of nodes of shortest paths.
460
461    ///Returns a reference to the NodeMap of the last but one nodes of the
462    ///shortest path tree.
463    ///\pre \ref run() must be called before using this function.
464    const PredNodeMap &predNodeMap() const { return *pred_node;}
465
466    ///Checks if a node is reachable from the root.
467
468    ///Returns \c true if \c v is reachable from the root.
469    ///\note The root node is reported to be reached!
470    ///\pre \ref run() must be called before using this function.
471    ///
472    bool reached(Node v) { return v==source || (*predecessor)[v]!=INVALID; }
473   
474  };
475
476  template<class GR,class LM>
477  class DijkstraWizardBase : public DijkstraDefaultTraits<GR,LM>
478  {
479
480    typedef DijkstraDefaultTraits<GR,LM> Base;
481  protected:
482    /// Pointer to the underlying graph.
483    void *_g;
484    /// Pointer to the length map
485    void *_length;
486    ///Pointer to the map of predecessors edges.
487    void *_pred;
488    ///Pointer to the map of predecessors nodes.
489    void *_predNode;
490    ///Pointer to the map of distances.
491    void *_dist;
492    ///Pointer to the source node.
493    void *_source;
494
495    typedef typename Base::Graph::Node Node;
496
497    public:
498    DijkstraWizardBase() : _g(0), _length(0), _pred(0), _predNode(0),
499                       _dist(0), _source(INVALID) {}
500
501    DijkstraWizardBase(const GR &g,const LM &l, Node s=INVALID) :
502      _g((void *)&g), _length((void *)&l), _pred(0), _predNode(0),
503                  _dist(0), _source((void *)&s) {}
504
505  };
506 
507  ///\e
508
509  ///\e
510  ///
511  template<class TR>
512  class DijkstraWizard : public TR
513  {
514    typedef TR Base;
515
516    ///The type of the underlying graph.
517    typedef typename TR::Graph Graph;
518    ///\e
519    typedef typename Graph::Node Node;
520    ///\e
521    typedef typename Graph::NodeIt NodeIt;
522    ///\e
523    typedef typename Graph::Edge Edge;
524    ///\e
525    typedef typename Graph::OutEdgeIt OutEdgeIt;
526   
527    ///The type of the map that stores the edge lengths.
528    typedef typename TR::LengthMap LengthMap;
529    ///The type of the length of the edges.
530    typedef typename LengthMap::Value Value;
531    ///\brief The type of the map that stores the last
532    ///edges of the shortest paths.
533    typedef typename TR::PredMap PredMap;
534    ///\brief The type of the map that stores the last but one
535    ///nodes of the shortest paths.
536    typedef typename TR::PredNodeMap PredNodeMap;
537    ///The type of the map that stores the dists of the nodes.
538    typedef typename TR::DistMap DistMap;
539
540    ///The heap type used by the dijkstra algorithm.
541    typedef typename TR::Heap Heap;
542public:
543    DijkstraWizard() : TR() {}
544
545    DijkstraWizard(const Graph &g,const LengthMap &l, Node s=INVALID) :
546      TR(g,l,s) {}
547
548    DijkstraWizard(const TR &b) : TR(b) {}
549
550    ~DijkstraWizard() {}
551
552    ///\e
553    void run()
554    {
555      Dijkstra<Graph,LengthMap,TR> Dij(*(Graph*)_g,*(LengthMap*)_length);
556      if(_pred) Dij.predMap(*(PredMap*)_pred);
557      if(_predNode) Dij.predNodeMap(*(PredNodeMap*)_predNode);
558      if(_dist) Dij.distMap(*(DistMap*)_dist);
559      Dij.run(*(Node*)_source);
560    }
561
562    ///\e
563    void run(Node s)
564    {
565      _source=(void *)&s;
566      run();
567    }
568
569    template<class T>
570    struct DefPredMapBase : public Base {
571      typedef T PredMap;
572      static PredMap *createPredMap(const Graph &G) { return 0; };
573      DefPredMapBase(const Base &b) : Base(b) {}
574    };
575   
576    ///\e
577    template<class T>
578    DijkstraWizard<DefPredMapBase<T> > predMap(const T &t)
579    {
580      _pred=(void *)&t;
581      return DijkstraWizard<DefPredMapBase<T> >(*this);
582    }
583   
584
585    template<class T>
586    struct DefPredNodeMapBase : public Base {
587      typedef T PredNodeMap;
588      static PredNodeMap *createPredNodeMap(const Graph &G) { return 0; };
589      DefPredNodeMapBase(const Base &b) : Base(b) {}
590    };
591   
592    ///\e
593    template<class T>
594    DijkstraWizard<DefPredNodeMapBase<T> > predNodeMap(const T &t)
595    {
596      _predNode=(void *)&t;
597      return DijkstraWizard<DefPredNodeMapBase<T> >(*this);
598    }
599   
600    template<class T>
601    struct DefDistMapBase : public Base {
602      typedef T DistMap;
603      static DistMap *createDistMap(const Graph &G) { return 0; };
604      DefDistMapBase(const Base &b) : Base(b) {}
605    };
606   
607    ///\e
608    template<class T>
609    DijkstraWizard<DefDistMapBase<T> > distMap(const T &t)
610    {
611      _dist=(void *)&t;
612      return DijkstraWizard<DefDistMapBase<T> >(*this);
613    }
614   
615    ///\e
616    DijkstraWizard<TR> &source(Node s)
617    {
618      source=(void *)&s;
619      return *this;
620    }
621   
622  };
623 
624  ///\e
625
626  ///\todo Please document...
627  ///
628  template<class GR, class LM>
629  DijkstraWizard<DijkstraWizardBase<GR,LM> >
630  dijkstra(const GR &g,const LM &l,typename GR::Node s=INVALID)
631  {
632    return DijkstraWizard<DijkstraWizardBase<GR,LM> >(g,l,s);
633  }
634
635/// @}
636 
637} //END OF NAMESPACE LEMON
638
639#endif
640
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