COIN-OR::LEMON - Graph Library

source: lemon-0.x/src/work/alpar/dijkstra.h @ 955:0a066f80e05f

Last change on this file since 955:0a066f80e05f was 955:0a066f80e05f, checked in by Alpar Juttner, 15 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 ReadMap concept.
46    ///
47    typedef LM LengthMap;
48    //The type of the length of the edges.
49    typedef typename LM::ValueType ValueType;
50    ///The heap type used by Dijkstra algorithm.
51    typedef BinHeap<typename Graph::Node,
52                    typename LM::ValueType,
53                    typename GR::template NodeMap<int>,
54                    std::less<ValueType> > Heap;
55
56    ///\brief The type of the map that stores the last
57    ///edges of the shortest paths.
58    ///
59    ///It must meet the \ref WriteMap concept.
60    ///
61    typedef typename Graph::template NodeMap<typename GR::Edge> PredMap;
62    ///Instantiates a PredMap.
63 
64    ///\todo Please document...
65    ///
66    static PredMap *createPredMap(const GR &G)
67    {
68      return new PredMap(G);
69    }
70    ///\brief The type of the map that stores the last but one
71    ///nodes of the shortest paths.
72    ///
73    ///It must meet the \ref WriteMap concept.
74    ///
75    typedef typename Graph::template NodeMap<typename GR::Node> PredNodeMap;
76    ///Instantiates a PredNodeMap.
77 
78    ///\todo Please document...
79    ///
80    static PredNodeMap *createPredNodeMap(const GR &G)
81    {
82      return new PredNodeMap(G);
83    }
84    ///The type of the map that stores the dists of the nodes.
85 
86    ///It must meet the \ref WriteMap concept.
87    ///
88    typedef typename Graph::template NodeMap<typename LM::ValueType> DistMap;
89    ///Instantiates a DistMap.
90 
91    ///\todo Please document...
92    ///
93    static DistMap *createDistMap(const GR &G)
94    {
95      return new DistMap(G);
96    }
97  };
98 
99  ///%Dijkstra algorithm class.
100
101  ///This class provides an efficient implementation of %Dijkstra algorithm.
102  ///The edge lengths are passed to the algorithm using a
103  ///\ref skeleton::ReadMap "ReadMap",
104  ///so it is easy to change it to any kind of length.
105  ///
106  ///The type of the length is determined by the
107  ///\ref skeleton::ReadMap::ValueType "ValueType" of the length map.
108  ///
109  ///It is also possible to change the underlying priority heap.
110  ///
111  ///\param GR The graph type the algorithm runs on. The default value is
112  ///\ref ListGraph. The value of GR is not used directly by Dijkstra, it
113  ///is only passed to \ref DijkstraDefaultTraits.
114  ///\param LM This read-only
115  ///EdgeMap
116  ///determines the
117  ///lengths of the edges. It is read once for each edge, so the map
118  ///may involve in relatively time consuming process to compute the edge
119  ///length if it is necessary. The default map type is
120  ///\ref skeleton::StaticGraph::EdgeMap "Graph::EdgeMap<int>".
121  ///The value of LM is not used directly by Dijkstra, it
122  ///is only passed to \ref DijkstraDefaultTraits.
123  ///\param TR Traits class to set various data types used by the algorithm.
124  ///The default traits class is
125  ///\ref DijkstraDefaultTraits "DijkstraDefaultTraits<GR,LM>".
126  ///See \ref DijkstraDefaultTraits for the documentation of
127  ///a Dijkstra traits class.
128  ///
129  ///\author Jacint Szabo and Alpar Juttner
130  ///\todo We need a typedef-names should be standardized. (-:
131
132#ifdef DOXYGEN
133  template <typename GR,
134            typename LM,
135            typename TR>
136#else
137  template <typename GR=ListGraph,
138            typename LM=typename GR::template EdgeMap<int>,
139            typename TR=DijkstraDefaultTraits<GR,LM> >
140#endif
141  class Dijkstra{
142  public:
143    typedef TR Traits;
144    ///The type of the underlying graph.
145    typedef typename TR::Graph Graph;
146    ///\e
147    typedef typename Graph::Node Node;
148    ///\e
149    typedef typename Graph::NodeIt NodeIt;
150    ///\e
151    typedef typename Graph::Edge Edge;
152    ///\e
153    typedef typename Graph::OutEdgeIt OutEdgeIt;
154   
155    ///The type of the length of the edges.
156    typedef typename TR::LengthMap::ValueType ValueType;
157    ///The type of the map that stores the edge lengths.
158    typedef typename TR::LengthMap LengthMap;
159    ///\brief The type of the map that stores the last
160    ///edges of the shortest paths.
161    typedef typename TR::PredMap PredMap;
162    ///\brief The type of the map that stores the last but one
163    ///nodes of the shortest paths.
164    typedef typename TR::PredNodeMap PredNodeMap;
165    ///The type of the map that stores the dists of the nodes.
166    typedef typename TR::DistMap DistMap;
167    ///The heap type used by the dijkstra algorithm.
168    typedef typename TR::Heap Heap;
169
170  private:
171    /// Pointer to the underlying graph.
172    const Graph *G;
173    /// Pointer to the length map
174    const LengthMap *length;
175    ///Pointer to the map of predecessors edges.
176    PredMap *predecessor;
177    ///Indicates if \ref predecessor is locally allocated (\c true) or not.
178    bool local_predecessor;
179    ///Pointer to the map of predecessors nodes.
180    PredNodeMap *pred_node;
181    ///Indicates if \ref pred_node is locally allocated (\c true) or not.
182    bool local_pred_node;
183    ///Pointer to the map of distances.
184    DistMap *distance;
185    ///Indicates if \ref distance is locally allocated (\c true) or not.
186    bool local_distance;
187
188    ///The source node of the last execution.
189    Node source;
190
191    ///Initializes the maps.
192   
193    ///\todo Error if \c G or are \c NULL. What about \c length?
194    ///\todo Better memory allocation (instead of new).
195    void init_maps()
196    {
197      if(!predecessor) {
198        local_predecessor = true;
199        predecessor = Traits::createPredMap(*G);
200      }
201      if(!pred_node) {
202        local_pred_node = true;
203        pred_node = Traits::createPredNodeMap(*G);
204      }
205      if(!distance) {
206        local_distance = true;
207        distance = Traits::createDistMap(*G);
208      }
209    }
210   
211  public :
212
213    template <class T>
214    struct SetPredMapTraits : public Traits {
215      typedef T PredMap;
216      ///\todo An exception should be thrown.
217      ///
218      static PredMap *createPredMap(const Graph &G)
219      {
220        std::cerr << __FILE__ ":" << __LINE__ <<
221          ": error: Special maps should be manually created" << std::endl;
222        exit(1);
223      }
224    };
225    ///\ref named-templ-param "Named parameter" for setting PredMap type
226
227    ///\ingroup flowalgs
228    ///\ref named-templ-param "Named parameter" for setting PredMap type
229    template <class T>
230    class SetPredMap : public Dijkstra< Graph,
231                                        LengthMap,
232                                        SetPredMapTraits<T> > { };
233   
234    template <class T>
235    struct SetPredNodeMapTraits : public Traits {
236      typedef T PredNodeMap;
237      ///\todo An exception should be thrown.
238      ///
239      static PredNodeMap *createPredNodeMap(const Graph &G)
240      {
241        std::cerr << __FILE__ ":" << __LINE__ <<
242          ": error: Special maps should be manually created" << std::endl;
243        exit(1);
244      }
245    };
246    ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
247
248    ///\ingroup flowalgs
249    ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
250    template <class T>
251    class SetPredNodeMap : public Dijkstra< Graph,
252                                            LengthMap,
253                                            SetPredNodeMapTraits<T> > { };
254   
255    template <class T>
256    struct SetDistMapTraits : public Traits {
257      typedef T DistMap;
258      ///\todo An exception should be thrown.
259      ///
260      static DistMap *createDistMap(const Graph &G)
261      {
262        std::cerr << __FILE__ ":" << __LINE__ <<
263          ": error: Special maps should be manually created" << std::endl;
264        exit(1);
265      }
266    };
267    ///\ref named-templ-param "Named parameter" for setting DistMap type
268
269    ///\ingroup flowalgs
270    ///\ref named-templ-param "Named parameter" for setting DistMap type
271    template <class T>
272    class SetDistMap : public Dijkstra< Graph,
273                                        LengthMap,
274                                        SetDistMapTraits<T> > { };
275   
276    ///Constructor.
277   
278    ///\param _G the graph the algorithm will run on.
279    ///\param _length the length map used by the algorithm.
280    Dijkstra(const Graph& _G, const LengthMap& _length) :
281      G(&_G), length(&_length),
282      predecessor(NULL), local_predecessor(false),
283      pred_node(NULL), local_pred_node(false),
284      distance(NULL), local_distance(false)
285    { }
286   
287    ///Destructor.
288    ~Dijkstra()
289    {
290      if(local_predecessor) delete predecessor;
291      if(local_pred_node) delete pred_node;
292      if(local_distance) delete distance;
293    }
294
295    ///Sets the length map.
296
297    ///Sets the length map.
298    ///\return <tt> (*this) </tt>
299    Dijkstra &setLengthMap(const LengthMap &m)
300    {
301      length = &m;
302      return *this;
303    }
304
305    ///Sets the map storing the predecessor edges.
306
307    ///Sets the map storing the predecessor edges.
308    ///If you don't use this function before calling \ref run(),
309    ///it will allocate one. The destuctor deallocates this
310    ///automatically allocated map, of course.
311    ///\return <tt> (*this) </tt>
312    Dijkstra &setPredMap(PredMap &m)
313    {
314      if(local_predecessor) {
315        delete predecessor;
316        local_predecessor=false;
317      }
318      predecessor = &m;
319      return *this;
320    }
321
322    ///Sets the map storing the predecessor nodes.
323
324    ///Sets the map storing the predecessor nodes.
325    ///If you don't use this function before calling \ref run(),
326    ///it will allocate one. The destuctor deallocates this
327    ///automatically allocated map, of course.
328    ///\return <tt> (*this) </tt>
329    Dijkstra &setPredNodeMap(PredNodeMap &m)
330    {
331      if(local_pred_node) {
332        delete pred_node;
333        local_pred_node=false;
334      }
335      pred_node = &m;
336      return *this;
337    }
338
339    ///Sets the map storing the distances calculated by the algorithm.
340
341    ///Sets the map storing the distances calculated by the algorithm.
342    ///If you don't use this function before calling \ref run(),
343    ///it will allocate one. The destuctor deallocates this
344    ///automatically allocated map, of course.
345    ///\return <tt> (*this) </tt>
346    Dijkstra &setDistMap(DistMap &m)
347    {
348      if(local_distance) {
349        delete distance;
350        local_distance=false;
351      }
352      distance = &m;
353      return *this;
354    }
355   
356  ///Runs %Dijkstra algorithm from node \c s.
357
358  ///This method runs the %Dijkstra algorithm from a root node \c s
359  ///in order to
360  ///compute the
361  ///shortest path to each node. The algorithm computes
362  ///- The shortest path tree.
363  ///- The distance of each node from the root.
364  ///\todo heap_map's type could also be in the traits class.
365    void run(Node s) {
366     
367      init_maps();
368     
369      source = s;
370     
371      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
372        predecessor->set(u,INVALID);
373        pred_node->set(u,INVALID);
374      }
375     
376      typename Graph::template NodeMap<int> heap_map(*G,-1);
377     
378      Heap heap(heap_map);
379     
380      heap.push(s,0);
381     
382      while ( !heap.empty() ) {
383       
384        Node v=heap.top();
385        ValueType oldvalue=heap[v];
386        heap.pop();
387        distance->set(v, oldvalue);
388       
389       
390        for(OutEdgeIt e(*G,v); e!=INVALID; ++e) {
391          Node w=G->head(e);
392          switch(heap.state(w)) {
393          case Heap::PRE_HEAP:
394            heap.push(w,oldvalue+(*length)[e]);
395            predecessor->set(w,e);
396            pred_node->set(w,v);
397            break;
398          case Heap::IN_HEAP:
399            if ( oldvalue+(*length)[e] < heap[w] ) {
400              heap.decrease(w, oldvalue+(*length)[e]);
401              predecessor->set(w,e);
402              pred_node->set(w,v);
403            }
404            break;
405          case Heap::POST_HEAP:
406            break;
407          }
408        }
409      }
410    }
411   
412    ///The distance of a node from the root.
413
414    ///Returns the distance of a node from the root.
415    ///\pre \ref run() must be called before using this function.
416    ///\warning If node \c v in unreachable from the root the return value
417    ///of this funcion is undefined.
418    ValueType dist(Node v) const { return (*distance)[v]; }
419
420    ///Returns the 'previous edge' of the shortest path tree.
421
422    ///For a node \c v it returns the 'previous edge' of the shortest path tree,
423    ///i.e. it returns the last edge of a shortest path from the root to \c
424    ///v. It is \ref INVALID
425    ///if \c v is unreachable from the root or if \c v=s. The
426    ///shortest path tree used here is equal to the shortest path tree used in
427    ///\ref predNode(Node v).  \pre \ref run() must be called before using
428    ///this function.
429    ///\todo predEdge could be a better name.
430    Edge pred(Node v) const { return (*predecessor)[v]; }
431
432    ///Returns the 'previous node' of the shortest path tree.
433
434    ///For a node \c v it returns the 'previous node' of the shortest path tree,
435    ///i.e. it returns the last but one node from a shortest path from the
436    ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
437    ///\c v=s. The shortest path tree used here is equal to the shortest path
438    ///tree used in \ref pred(Node v).  \pre \ref run() must be called before
439    ///using this function.
440    Node predNode(Node v) const { return (*pred_node)[v]; }
441   
442    ///Returns a reference to the NodeMap of distances.
443
444    ///Returns a reference to the NodeMap of distances. \pre \ref run() must
445    ///be called before using this function.
446    const DistMap &distMap() const { return *distance;}
447 
448    ///Returns a reference to the shortest path tree map.
449
450    ///Returns a reference to the NodeMap of the edges of the
451    ///shortest path tree.
452    ///\pre \ref run() must be called before using this function.
453    const PredMap &predMap() const { return *predecessor;}
454 
455    ///Returns a reference to the map of nodes of shortest paths.
456
457    ///Returns a reference to the NodeMap of the last but one nodes of the
458    ///shortest path tree.
459    ///\pre \ref run() must be called before using this function.
460    const PredNodeMap &predNodeMap() const { return *pred_node;}
461
462    ///Checks if a node is reachable from the root.
463
464    ///Returns \c true if \c v is reachable from the root.
465    ///\note The root node is reported to be reached!
466    ///\pre \ref run() must be called before using this function.
467    ///
468    bool reached(Node v) { return v==source || (*predecessor)[v]!=INVALID; }
469   
470  };
471
472  ///\e
473
474  ///\e
475  ///
476  template<class TR>
477  class _Dijkstra
478  {
479    typedef TR Traits;
480
481    ///The type of the underlying graph.
482    typedef typename TR::Graph Graph;
483    ///\e
484    typedef typename Graph::Node Node;
485    ///\e
486    typedef typename Graph::NodeIt NodeIt;
487    ///\e
488    typedef typename Graph::Edge Edge;
489    ///\e
490    typedef typename Graph::OutEdgeIt OutEdgeIt;
491   
492    ///The type of the map that stores the edge lengths.
493    typedef typename TR::LengthMap LengthMap;
494    ///The type of the length of the edges.
495    typedef typename LengthMap::ValueType ValueType;
496    ///\brief The type of the map that stores the last
497    ///edges of the shortest paths.
498    typedef typename TR::PredMap PredMap;
499    ///\brief The type of the map that stores the last but one
500    ///nodes of the shortest paths.
501    typedef typename TR::PredNodeMap PredNodeMap;
502    ///The type of the map that stores the dists of the nodes.
503    typedef typename TR::DistMap DistMap;
504
505    ///The heap type used by the dijkstra algorithm.
506    typedef typename TR::Heap Heap;
507
508    /// Pointer to the underlying graph.
509    const Graph *G;
510    /// Pointer to the length map
511    const LengthMap *length;
512    ///Pointer to the map of predecessors edges.
513    PredMap *predecessor;
514    ///Pointer to the map of predecessors nodes.
515    PredNodeMap *pred_node;
516    ///Pointer to the map of distances.
517    DistMap *distance;
518   
519    Node source;
520   
521public:
522    _Dijkstra() : G(0), length(0), predecessor(0), pred_node(0),
523                  distance(0), source(INVALID) {}
524
525    _Dijkstra(const Graph &g,const LengthMap &l, Node s) :
526      G(&g), length(&l), predecessor(0), pred_node(0),
527                  distance(0), source(s) {}
528
529    ~_Dijkstra()
530    {
531      Dijkstra<Graph,LengthMap,TR> Dij(*G,*length);
532      if(predecessor) Dij.setPredMap(*predecessor);
533      if(pred_node) Dij.setPredNodeMap(*pred_node);
534      if(distance) Dij.setDistMap(*distance);
535      Dij.run(source);
536    }
537
538    template<class T>
539    struct SetPredMapTraits : public Traits {typedef T PredMap;};
540   
541    ///\e
542    template<class T>
543    _Dijkstra<SetPredMapTraits<T> > setPredMap(const T &t)
544    {
545      _Dijkstra<SetPredMapTraits<T> > r;
546      r.G=G;
547      r.length=length;
548      r.predecessor=&t;
549      r.pred_node=pred_node;
550      r.distance=distance;
551      r.source=source;
552      return r;
553    }
554   
555    template<class T>
556    struct SetPredNodeMapTraits :public Traits {typedef T PredNodeMap;};
557    ///\e
558    template<class T>
559    _Dijkstra<SetPredNodeMapTraits<T> > setPredNodeMap(const T &t)
560    {
561      _Dijkstra<SetPredNodeMapTraits<T> > r;
562      r.G=G;
563      r.length=length;
564      r.predecessor=predecessor;
565      r.pred_node=&t;
566      r.distance=distance;
567      r.source=source;
568      return r;
569    }
570   
571    template<class T>
572    struct SetDistMapTraits : public Traits {typedef T DistMap;};
573    ///\e
574    template<class T>
575    _Dijkstra<SetDistMapTraits<T> > setDistMap(const T &t)
576    {
577      _Dijkstra<SetPredMapTraits<T> > r;
578      r.G=G;
579      r.length=length;
580      r.predecessor=predecessor;
581      r.pred_node=pred_node;
582      r.distance=&t;
583      r.source=source;
584      return r;
585    }
586   
587    ///\e
588    _Dijkstra<TR> &setSource(Node s)
589    {
590      source=s;
591      return *this;
592    }
593   
594  };
595 
596  ///\e
597
598  ///\todo Please document...
599  ///
600  template<class GR, class LM>
601  _Dijkstra<DijkstraDefaultTraits<GR,LM> >
602  dijkstra(const GR &g,const LM &l,typename GR::Node s)
603  {
604    return _Dijkstra<DijkstraDefaultTraits<GR,LM> >(g,l,s);
605  }
606
607/// @}
608 
609} //END OF NAMESPACE LEMON
610
611#endif
612
613
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