COIN-OR::LEMON - Graph Library

source: lemon-0.x/src/work/alpar/dijkstra.h @ 987:87f7c54892df

Last change on this file since 987:87f7c54892df was 987:87f7c54892df, checked in by Alpar Juttner, 16 years ago

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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 SetPredMapTraits : 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    ///\relates Dijkstra
232    ///\ingroup flowalgs
233    ///\ref named-templ-param "Named parameter" for setting PredMap type
234    template <class T>
235    class SetPredMap : public Dijkstra< Graph,
236                                        LengthMap,
237                                        SetPredMapTraits<T> > { };
238   
239    template <class T>
240    struct SetPredNodeMapTraits : public Traits {
241      typedef T PredNodeMap;
242      ///\todo An exception should be thrown.
243      ///
244      static PredNodeMap *createPredNodeMap(const Graph &G)
245      {
246        std::cerr << __FILE__ ":" << __LINE__ <<
247          ": error: Special maps should be manually created" << std::endl;
248        exit(1);
249      }
250    };
251    ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
252
253    ///\ingroup flowalgs
254    ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
255    template <class T>
256    class SetPredNodeMap : public Dijkstra< Graph,
257                                            LengthMap,
258                                            SetPredNodeMapTraits<T> > { };
259   
260    template <class T>
261    struct SetDistMapTraits : public Traits {
262      typedef T DistMap;
263      ///\todo An exception should be thrown.
264      ///
265      static DistMap *createDistMap(const Graph &G)
266      {
267        std::cerr << __FILE__ ":" << __LINE__ <<
268          ": error: Special maps should be manually created" << std::endl;
269        exit(1);
270      }
271    };
272    ///\ref named-templ-param "Named parameter" for setting DistMap type
273
274    ///\ingroup flowalgs
275    ///\ref named-templ-param "Named parameter" for setting DistMap type
276    template <class T>
277    class SetDistMap : public Dijkstra< Graph,
278                                        LengthMap,
279                                        SetDistMapTraits<T> > { };
280   
281    ///Constructor.
282   
283    ///\param _G the graph the algorithm will run on.
284    ///\param _length the length map used by the algorithm.
285    Dijkstra(const Graph& _G, const LengthMap& _length) :
286      G(&_G), length(&_length),
287      predecessor(NULL), local_predecessor(false),
288      pred_node(NULL), local_pred_node(false),
289      distance(NULL), local_distance(false)
290    { }
291   
292    ///Destructor.
293    ~Dijkstra()
294    {
295      if(local_predecessor) delete predecessor;
296      if(local_pred_node) delete pred_node;
297      if(local_distance) delete distance;
298    }
299
300    ///Sets the length map.
301
302    ///Sets the length map.
303    ///\return <tt> (*this) </tt>
304    Dijkstra &setLengthMap(const LengthMap &m)
305    {
306      length = &m;
307      return *this;
308    }
309
310    ///Sets the map storing the predecessor edges.
311
312    ///Sets the map storing the predecessor edges.
313    ///If you don't use this function before calling \ref run(),
314    ///it will allocate one. The destuctor deallocates this
315    ///automatically allocated map, of course.
316    ///\return <tt> (*this) </tt>
317    Dijkstra &setPredMap(PredMap &m)
318    {
319      if(local_predecessor) {
320        delete predecessor;
321        local_predecessor=false;
322      }
323      predecessor = &m;
324      return *this;
325    }
326
327    ///Sets the map storing the predecessor nodes.
328
329    ///Sets the map storing the predecessor nodes.
330    ///If you don't use this function before calling \ref run(),
331    ///it will allocate one. The destuctor deallocates this
332    ///automatically allocated map, of course.
333    ///\return <tt> (*this) </tt>
334    Dijkstra &setPredNodeMap(PredNodeMap &m)
335    {
336      if(local_pred_node) {
337        delete pred_node;
338        local_pred_node=false;
339      }
340      pred_node = &m;
341      return *this;
342    }
343
344    ///Sets the map storing the distances calculated by the algorithm.
345
346    ///Sets the map storing the distances calculated by the algorithm.
347    ///If you don't use this function before calling \ref run(),
348    ///it will allocate one. The destuctor deallocates this
349    ///automatically allocated map, of course.
350    ///\return <tt> (*this) </tt>
351    Dijkstra &setDistMap(DistMap &m)
352    {
353      if(local_distance) {
354        delete distance;
355        local_distance=false;
356      }
357      distance = &m;
358      return *this;
359    }
360   
361  ///Runs %Dijkstra algorithm from node \c s.
362
363  ///This method runs the %Dijkstra algorithm from a root node \c s
364  ///in order to
365  ///compute the
366  ///shortest path to each node. The algorithm computes
367  ///- The shortest path tree.
368  ///- The distance of each node from the root.
369  ///\todo heap_map's type could also be in the traits class.
370    void run(Node s) {
371     
372      init_maps();
373     
374      source = s;
375     
376      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
377        predecessor->set(u,INVALID);
378        pred_node->set(u,INVALID);
379      }
380     
381      typename Graph::template NodeMap<int> heap_map(*G,-1);
382     
383      Heap heap(heap_map);
384     
385      heap.push(s,0);
386     
387      while ( !heap.empty() ) {
388       
389        Node v=heap.top();
390        Value oldvalue=heap[v];
391        heap.pop();
392        distance->set(v, oldvalue);
393       
394       
395        for(OutEdgeIt e(*G,v); e!=INVALID; ++e) {
396          Node w=G->target(e);
397          switch(heap.state(w)) {
398          case Heap::PRE_HEAP:
399            heap.push(w,oldvalue+(*length)[e]);
400            predecessor->set(w,e);
401            pred_node->set(w,v);
402            break;
403          case Heap::IN_HEAP:
404            if ( oldvalue+(*length)[e] < heap[w] ) {
405              heap.decrease(w, oldvalue+(*length)[e]);
406              predecessor->set(w,e);
407              pred_node->set(w,v);
408            }
409            break;
410          case Heap::POST_HEAP:
411            break;
412          }
413        }
414      }
415    }
416   
417    ///The distance of a node from the root.
418
419    ///Returns the distance of a node from the root.
420    ///\pre \ref run() must be called before using this function.
421    ///\warning If node \c v in unreachable from the root the return value
422    ///of this funcion is undefined.
423    Value dist(Node v) const { return (*distance)[v]; }
424
425    ///Returns the 'previous edge' of the shortest path tree.
426
427    ///For a node \c v it returns the 'previous edge' of the shortest path tree,
428    ///i.e. it returns the last edge of a shortest path from the root to \c
429    ///v. It is \ref INVALID
430    ///if \c v is unreachable from the root or if \c v=s. The
431    ///shortest path tree used here is equal to the shortest path tree used in
432    ///\ref predNode(Node v).  \pre \ref run() must be called before using
433    ///this function.
434    ///\todo predEdge could be a better name.
435    Edge pred(Node v) const { return (*predecessor)[v]; }
436
437    ///Returns the 'previous node' of the shortest path tree.
438
439    ///For a node \c v it returns the 'previous node' of the shortest path tree,
440    ///i.e. it returns the last but one node from a shortest path from the
441    ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
442    ///\c v=s. The shortest path tree used here is equal to the shortest path
443    ///tree used in \ref pred(Node v).  \pre \ref run() must be called before
444    ///using this function.
445    Node predNode(Node v) const { return (*pred_node)[v]; }
446   
447    ///Returns a reference to the NodeMap of distances.
448
449    ///Returns a reference to the NodeMap of distances. \pre \ref run() must
450    ///be called before using this function.
451    const DistMap &distMap() const { return *distance;}
452 
453    ///Returns a reference to the shortest path tree map.
454
455    ///Returns a reference to the NodeMap of the edges of the
456    ///shortest path tree.
457    ///\pre \ref run() must be called before using this function.
458    const PredMap &predMap() const { return *predecessor;}
459 
460    ///Returns a reference to the map of nodes of shortest paths.
461
462    ///Returns a reference to the NodeMap of the last but one nodes of the
463    ///shortest path tree.
464    ///\pre \ref run() must be called before using this function.
465    const PredNodeMap &predNodeMap() const { return *pred_node;}
466
467    ///Checks if a node is reachable from the root.
468
469    ///Returns \c true if \c v is reachable from the root.
470    ///\note The root node is reported to be reached!
471    ///\pre \ref run() must be called before using this function.
472    ///
473    bool reached(Node v) { return v==source || (*predecessor)[v]!=INVALID; }
474   
475  };
476
477  ///\e
478
479  ///\e
480  ///
481  template<class TR>
482  class _Dijkstra
483  {
484    typedef TR Traits;
485
486    ///The type of the underlying graph.
487    typedef typename TR::Graph Graph;
488    ///\e
489    typedef typename Graph::Node Node;
490    ///\e
491    typedef typename Graph::NodeIt NodeIt;
492    ///\e
493    typedef typename Graph::Edge Edge;
494    ///\e
495    typedef typename Graph::OutEdgeIt OutEdgeIt;
496   
497    ///The type of the map that stores the edge lengths.
498    typedef typename TR::LengthMap LengthMap;
499    ///The type of the length of the edges.
500    typedef typename LengthMap::Value Value;
501    ///\brief The type of the map that stores the last
502    ///edges of the shortest paths.
503    typedef typename TR::PredMap PredMap;
504    ///\brief The type of the map that stores the last but one
505    ///nodes of the shortest paths.
506    typedef typename TR::PredNodeMap PredNodeMap;
507    ///The type of the map that stores the dists of the nodes.
508    typedef typename TR::DistMap DistMap;
509
510    ///The heap type used by the dijkstra algorithm.
511    typedef typename TR::Heap Heap;
512
513    /// Pointer to the underlying graph.
514    const Graph *G;
515    /// Pointer to the length map
516    const LengthMap *length;
517    ///Pointer to the map of predecessors edges.
518    PredMap *predecessor;
519    ///Pointer to the map of predecessors nodes.
520    PredNodeMap *pred_node;
521    ///Pointer to the map of distances.
522    DistMap *distance;
523   
524    Node source;
525   
526public:
527    _Dijkstra() : G(0), length(0), predecessor(0), pred_node(0),
528                  distance(0), source(INVALID) {}
529
530    _Dijkstra(const Graph &g,const LengthMap &l, Node s) :
531      G(&g), length(&l), predecessor(0), pred_node(0),
532                  distance(0), source(s) {}
533
534    ~_Dijkstra()
535    {
536      Dijkstra<Graph,LengthMap,TR> Dij(*G,*length);
537      if(predecessor) Dij.setPredMap(*predecessor);
538      if(pred_node) Dij.setPredNodeMap(*pred_node);
539      if(distance) Dij.setDistMap(*distance);
540      Dij.run(source);
541    }
542
543    template<class T>
544    struct SetPredMapTraits : public Traits {typedef T PredMap;};
545   
546    ///\e
547    template<class T>
548    _Dijkstra<SetPredMapTraits<T> > setPredMap(const T &t)
549    {
550      _Dijkstra<SetPredMapTraits<T> > r;
551      r.G=G;
552      r.length=length;
553      r.predecessor=&t;
554      r.pred_node=pred_node;
555      r.distance=distance;
556      r.source=source;
557      return r;
558    }
559   
560    template<class T>
561    struct SetPredNodeMapTraits :public Traits {typedef T PredNodeMap;};
562    ///\e
563    template<class T>
564    _Dijkstra<SetPredNodeMapTraits<T> > setPredNodeMap(const T &t)
565    {
566      _Dijkstra<SetPredNodeMapTraits<T> > r;
567      r.G=G;
568      r.length=length;
569      r.predecessor=predecessor;
570      r.pred_node=&t;
571      r.distance=distance;
572      r.source=source;
573      return r;
574    }
575   
576    template<class T>
577    struct SetDistMapTraits : public Traits {typedef T DistMap;};
578    ///\e
579    template<class T>
580    _Dijkstra<SetDistMapTraits<T> > setDistMap(const T &t)
581    {
582      _Dijkstra<SetPredMapTraits<T> > r;
583      r.G=G;
584      r.length=length;
585      r.predecessor=predecessor;
586      r.pred_node=pred_node;
587      r.distance=&t;
588      r.source=source;
589      return r;
590    }
591   
592    ///\e
593    _Dijkstra<TR> &setSource(Node s)
594    {
595      source=s;
596      return *this;
597    }
598   
599  };
600 
601  ///\e
602
603  ///\todo Please document...
604  ///
605  template<class GR, class LM>
606  _Dijkstra<DijkstraDefaultTraits<GR,LM> >
607  dijkstra(const GR &g,const LM &l,typename GR::Node s)
608  {
609    return _Dijkstra<DijkstraDefaultTraits<GR,LM> >(g,l,s);
610  }
611
612/// @}
613 
614} //END OF NAMESPACE LEMON
615
616#endif
617
618
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