alpar@255: // -*- C++ -*-
alpar@255: #ifndef HUGO_DIJKSTRA_H
alpar@255: #define HUGO_DIJKSTRA_H
alpar@255: 
alpar@758: ///\ingroup flowalgs
alpar@255: ///\file
alpar@255: ///\brief Dijkstra algorithm.
alpar@255: 
ladanyi@542: #include <hugo/bin_heap.h>
ladanyi@542: #include <hugo/invalid.h>
alpar@255: 
alpar@255: namespace hugo {
jacint@385: 
alpar@758: /// \addtogroup flowalgs
alpar@430: /// @{
alpar@430: 
alpar@255:   ///%Dijkstra algorithm class.
alpar@255: 
alpar@255:   ///This class provides an efficient implementation of %Dijkstra algorithm.
alpar@255:   ///The edge lengths are passed to the algorithm using a
alpar@255:   ///\ref ReadMapSkeleton "readable map",
alpar@255:   ///so it is easy to change it to any kind of length.
alpar@255:   ///
alpar@255:   ///The type of the length is determined by the \c ValueType of the length map.
alpar@255:   ///
alpar@255:   ///It is also possible to change the underlying priority heap.
alpar@255:   ///
alpar@584:   ///\param GR The graph type the algorithm runs on.
alpar@584:   ///\param LM This read-only
jacint@385:   ///EdgeMap
jacint@385:   ///determines the
jacint@385:   ///lengths of the edges. It is read once for each edge, so the map
jacint@385:   ///may involve in relatively time consuming process to compute the edge
jacint@385:   ///length if it is necessary. The default map type is
jacint@385:   ///\ref GraphSkeleton::EdgeMap "Graph::EdgeMap<int>"
jacint@385:   ///\param Heap The heap type used by the %Dijkstra
jacint@385:   ///algorithm. The default
jacint@385:   ///is using \ref BinHeap "binary heap".
alpar@456:   ///
alpar@689:   ///\author Jacint Szabo and Alpar Juttner
alpar@693:   ///\todo We need a typedef-names should be standardized. (-:
alpar@734:   ///\todo Type of \c PredMap, \c PredNodeMap and \c DistMap
alpar@734:   ///should not be fixed. (Problematic to solve).
alpar@584: 
alpar@255: #ifdef DOXYGEN
alpar@584:   template <typename GR,
alpar@584: 	    typename LM,
alpar@255: 	    typename Heap>
alpar@255: #else
alpar@584:   template <typename GR,
alpar@584: 	    typename LM=typename GR::template EdgeMap<int>,
alpar@532: 	    template <class,class,class,class> class Heap = BinHeap >
alpar@255: #endif
alpar@255:   class Dijkstra{
alpar@255:   public:
alpar@584:     ///The type of the underlying graph.
alpar@584:     typedef GR Graph;
alpar@255:     typedef typename Graph::Node Node;
alpar@255:     typedef typename Graph::NodeIt NodeIt;
alpar@255:     typedef typename Graph::Edge Edge;
alpar@255:     typedef typename Graph::OutEdgeIt OutEdgeIt;
alpar@255:     
alpar@584:     ///The type of the length of the edges.
alpar@584:     typedef typename LM::ValueType ValueType;
alpar@693:     ///The type of the map that stores the edge lengths.
alpar@584:     typedef LM LengthMap;
alpar@693:     ///\brief The type of the map that stores the last
alpar@584:     ///edges of the shortest paths.
marci@433:     typedef typename Graph::template NodeMap<Edge> PredMap;
alpar@693:     ///\brief The type of the map that stores the last but one
alpar@584:     ///nodes of the shortest paths.
marci@433:     typedef typename Graph::template NodeMap<Node> PredNodeMap;
alpar@693:     ///The type of the map that stores the dists of the nodes.
marci@433:     typedef typename Graph::template NodeMap<ValueType> DistMap;
alpar@255: 
alpar@255:   private:
alpar@688:     const Graph *G;
alpar@688:     const LM *length;
alpar@688:     //    bool local_length;
alpar@688:     PredMap *predecessor;
alpar@688:     bool local_predecessor;
alpar@688:     PredNodeMap *pred_node;
alpar@688:     bool local_pred_node;
alpar@688:     DistMap *distance;
alpar@688:     bool local_distance;
alpar@688: 
alpar@774:     //The source node of the last execution.
alpar@774:     Node source;
alpar@774: 
alpar@785:     ///Initializes the maps.
alpar@688:     
alpar@694:     ///\todo Error if \c G or are \c NULL. What about \c length?
alpar@688:     ///\todo Better memory allocation (instead of new).
alpar@688:     void init_maps() 
alpar@688:     {
alpar@688: //       if(!length) {
alpar@688: // 	local_length = true;
alpar@688: // 	length = new LM(G);
alpar@688: //       }
alpar@688:       if(!predecessor) {
alpar@688: 	local_predecessor = true;
alpar@688: 	predecessor = new PredMap(*G);
alpar@688:       }
alpar@688:       if(!pred_node) {
alpar@688: 	local_pred_node = true;
alpar@688: 	pred_node = new PredNodeMap(*G);
alpar@688:       }
alpar@688:       if(!distance) {
alpar@688: 	local_distance = true;
alpar@688: 	distance = new DistMap(*G);
alpar@688:       }
alpar@688:     }
alpar@255:     
alpar@255:   public :
alpar@255:     
alpar@584:     Dijkstra(const Graph& _G, const LM& _length) :
alpar@688:       G(&_G), length(&_length),
alpar@707:       predecessor(NULL), local_predecessor(false),
alpar@707:       pred_node(NULL), local_pred_node(false),
alpar@707:       distance(NULL), local_distance(false)
alpar@688:     { }
alpar@688:     
alpar@688:     ~Dijkstra() 
alpar@688:     {
alpar@688:       //      if(local_length) delete length;
alpar@688:       if(local_predecessor) delete predecessor;
alpar@688:       if(local_pred_node) delete pred_node;
alpar@688:       if(local_distance) delete distance;
alpar@688:     }
alpar@688: 
alpar@688:     ///Sets the graph the algorithm will run on.
alpar@688: 
alpar@688:     ///Sets the graph the algorithm will run on.
alpar@688:     ///\return <tt> (*this) </tt>
alpar@785:     ///\bug What about maps?
alpar@785:     ///\todo It may be unnecessary
alpar@688:     Dijkstra &setGraph(const Graph &_G) 
alpar@688:     {
alpar@688:       G = &_G;
alpar@688:       return *this;
alpar@688:     }
alpar@688:     ///Sets the length map.
alpar@688: 
alpar@688:     ///Sets the length map.
alpar@688:     ///\return <tt> (*this) </tt>
alpar@688:     Dijkstra &setLengthMap(const LM &m) 
alpar@688:     {
alpar@688: //       if(local_length) {
alpar@688: // 	delete length;
alpar@688: // 	local_length=false;
alpar@688: //       }
alpar@688:       length = &m;
alpar@688:       return *this;
alpar@688:     }
alpar@688: 
alpar@688:     ///Sets the map storing the predecessor edges.
alpar@688: 
alpar@688:     ///Sets the map storing the predecessor edges.
alpar@688:     ///If you don't use this function before calling \ref run(),
alpar@688:     ///it will allocate one. The destuctor deallocates this
alpar@688:     ///automatically allocated map, of course.
alpar@688:     ///\return <tt> (*this) </tt>
alpar@688:     Dijkstra &setPredMap(PredMap &m) 
alpar@688:     {
alpar@688:       if(local_predecessor) {
alpar@688: 	delete predecessor;
alpar@688: 	local_predecessor=false;
alpar@688:       }
alpar@688:       predecessor = &m;
alpar@688:       return *this;
alpar@688:     }
alpar@688: 
alpar@688:     ///Sets the map storing the predecessor nodes.
alpar@688: 
alpar@688:     ///Sets the map storing the predecessor nodes.
alpar@688:     ///If you don't use this function before calling \ref run(),
alpar@688:     ///it will allocate one. The destuctor deallocates this
alpar@688:     ///automatically allocated map, of course.
alpar@688:     ///\return <tt> (*this) </tt>
alpar@688:     Dijkstra &setPredNodeMap(PredNodeMap &m) 
alpar@688:     {
alpar@688:       if(local_pred_node) {
alpar@688: 	delete pred_node;
alpar@688: 	local_pred_node=false;
alpar@688:       }
alpar@688:       pred_node = &m;
alpar@688:       return *this;
alpar@688:     }
alpar@688: 
alpar@688:     ///Sets the map storing the distances calculated by the algorithm.
alpar@688: 
alpar@688:     ///Sets the map storing the distances calculated by the algorithm.
alpar@688:     ///If you don't use this function before calling \ref run(),
alpar@688:     ///it will allocate one. The destuctor deallocates this
alpar@688:     ///automatically allocated map, of course.
alpar@688:     ///\return <tt> (*this) </tt>
alpar@688:     Dijkstra &setDistMap(DistMap &m) 
alpar@688:     {
alpar@688:       if(local_distance) {
alpar@688: 	delete distance;
alpar@688: 	local_distance=false;
alpar@688:       }
alpar@688:       distance = &m;
alpar@688:       return *this;
alpar@688:     }
alpar@255:     
alpar@694:   ///Runs %Dijkstra algorithm from node \c s.
alpar@694: 
alpar@694:   ///This method runs the %Dijkstra algorithm from a root node \c s
alpar@694:   ///in order to
alpar@694:   ///compute the
alpar@694:   ///shortest path to each node. The algorithm computes
alpar@694:   ///- The shortest path tree.
alpar@694:   ///- The distance of each node from the root.
alpar@694:     
alpar@694:     void run(Node s) {
alpar@694:       
alpar@694:       init_maps();
alpar@694:       
alpar@774:       source = s;
alpar@774:       
alpar@774:       for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
alpar@694: 	predecessor->set(u,INVALID);
alpar@694: 	pred_node->set(u,INVALID);
alpar@694:       }
alpar@694:       
alpar@694:       typename GR::template NodeMap<int> heap_map(*G,-1);
alpar@694:       
alpar@694:       typedef Heap<Node, ValueType, typename GR::template NodeMap<int>,
alpar@694:       std::less<ValueType> > 
alpar@694:       HeapType;
alpar@694:       
alpar@694:       HeapType heap(heap_map);
alpar@694:       
alpar@694:       heap.push(s,0); 
alpar@694:       
alpar@694:       while ( !heap.empty() ) {
alpar@694: 	
alpar@694: 	Node v=heap.top(); 
alpar@694: 	ValueType oldvalue=heap[v];
alpar@694: 	heap.pop();
alpar@694: 	distance->set(v, oldvalue);
alpar@694: 	
alpar@694: 	
alpar@774: 	for(OutEdgeIt e(*G,v); e!=INVALID; ++e) {
alpar@774: 	  Node w=G->head(e); 
alpar@694: 	  switch(heap.state(w)) {
alpar@694: 	  case HeapType::PRE_HEAP:
alpar@694: 	    heap.push(w,oldvalue+(*length)[e]); 
alpar@694: 	    predecessor->set(w,e);
alpar@694: 	    pred_node->set(w,v);
alpar@694: 	    break;
alpar@694: 	  case HeapType::IN_HEAP:
alpar@694: 	    if ( oldvalue+(*length)[e] < heap[w] ) {
alpar@694: 	      heap.decrease(w, oldvalue+(*length)[e]); 
alpar@694: 	      predecessor->set(w,e);
alpar@694: 	      pred_node->set(w,v);
alpar@694: 	    }
alpar@694: 	    break;
alpar@694: 	  case HeapType::POST_HEAP:
alpar@694: 	    break;
alpar@694: 	  }
alpar@694: 	}
alpar@694:       }
alpar@694:     }
alpar@255:     
jacint@385:     ///The distance of a node from the root.
alpar@255: 
jacint@385:     ///Returns the distance of a node from the root.
alpar@255:     ///\pre \ref run() must be called before using this function.
jacint@385:     ///\warning If node \c v in unreachable from the root the return value
alpar@255:     ///of this funcion is undefined.
alpar@688:     ValueType dist(Node v) const { return (*distance)[v]; }
jacint@373: 
alpar@584:     ///Returns the 'previous edge' of the shortest path tree.
alpar@255: 
alpar@584:     ///For a node \c v it returns the 'previous edge' of the shortest path tree,
alpar@785:     ///i.e. it returns the last edge of a shortest path from the root to \c
alpar@688:     ///v. It is \ref INVALID
alpar@688:     ///if \c v is unreachable from the root or if \c v=s. The
jacint@385:     ///shortest path tree used here is equal to the shortest path tree used in
jacint@385:     ///\ref predNode(Node v).  \pre \ref run() must be called before using
jacint@385:     ///this function.
alpar@780:     ///\todo predEdge could be a better name.
alpar@688:     Edge pred(Node v) const { return (*predecessor)[v]; }
jacint@373: 
alpar@584:     ///Returns the 'previous node' of the shortest path tree.
alpar@255: 
alpar@584:     ///For a node \c v it returns the 'previous node' of the shortest path tree,
jacint@385:     ///i.e. it returns the last but one node from a shortest path from the
jacint@385:     ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
jacint@385:     ///\c v=s. The shortest path tree used here is equal to the shortest path
jacint@385:     ///tree used in \ref pred(Node v).  \pre \ref run() must be called before
jacint@385:     ///using this function.
alpar@688:     Node predNode(Node v) const { return (*pred_node)[v]; }
alpar@255:     
alpar@255:     ///Returns a reference to the NodeMap of distances.
alpar@255: 
jacint@385:     ///Returns a reference to the NodeMap of distances. \pre \ref run() must
jacint@385:     ///be called before using this function.
alpar@688:     const DistMap &distMap() const { return *distance;}
jacint@385:  
alpar@255:     ///Returns a reference to the shortest path tree map.
alpar@255: 
alpar@255:     ///Returns a reference to the NodeMap of the edges of the
alpar@255:     ///shortest path tree.
alpar@255:     ///\pre \ref run() must be called before using this function.
alpar@688:     const PredMap &predMap() const { return *predecessor;}
jacint@385:  
jacint@385:     ///Returns a reference to the map of nodes of shortest paths.
alpar@255: 
alpar@255:     ///Returns a reference to the NodeMap of the last but one nodes of the
jacint@385:     ///shortest path tree.
alpar@255:     ///\pre \ref run() must be called before using this function.
alpar@688:     const PredNodeMap &predNodeMap() const { return *pred_node;}
alpar@255: 
jacint@385:     ///Checks if a node is reachable from the root.
alpar@255: 
jacint@385:     ///Returns \c true if \c v is reachable from the root.
alpar@774:     ///\warning the root node is reported to be reached!
alpar@255:     ///\pre \ref run() must be called before using this function.
jacint@385:     ///
alpar@780:     bool reached(Node v) { return v==source || (*predecessor)[v]!=INVALID; }
alpar@255:     
alpar@255:   };
alpar@255:   
alpar@430: /// @}
alpar@255:   
alpar@255: } //END OF NAMESPACE HUGO
alpar@255: 
alpar@255: #endif
alpar@255: 
alpar@255: