alpar@255: // -*- C++ -*-
alpar@255: #ifndef HUGO_DIJKSTRA_H
alpar@255: #define HUGO_DIJKSTRA_H
alpar@255: 
alpar@430: ///ingroup galgs
alpar@255: ///\file
alpar@255: ///\brief Dijkstra algorithm.
alpar@255: 
klao@258: #include <bin_heap.h>
alpar@257: #include <invalid.h>
alpar@255: 
alpar@255: namespace hugo {
jacint@385: 
alpar@430: /// \addtogroup galgs
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:   ///
jacint@385:   ///\param Graph The graph type the algorithm runs on.
jacint@385:   ///\param LengthMap 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@456:   ///\author Jacint Szabo
alpar@255: #ifdef DOXYGEN
alpar@255:   template <typename Graph,
alpar@255: 	    typename LengthMap,
alpar@255: 	    typename Heap>
alpar@255: #else
alpar@255:   template <typename Graph,
marci@433: 	    typename LengthMap=typename Graph::template EdgeMap<int>,
alpar@255: 	    template <class,class,class> class Heap = BinHeap >
alpar@255: #endif
alpar@255:   class Dijkstra{
alpar@255:   public:
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@255:     typedef typename LengthMap::ValueType ValueType;
marci@433:     typedef typename Graph::template NodeMap<Edge> PredMap;
marci@433:     typedef typename Graph::template NodeMap<Node> PredNodeMap;
marci@433:     typedef typename Graph::template NodeMap<ValueType> DistMap;
alpar@255: 
alpar@255:   private:
alpar@255:     const Graph& G;
alpar@255:     const LengthMap& length;
alpar@255:     PredMap predecessor;
alpar@255:     PredNodeMap pred_node;
alpar@255:     DistMap distance;
alpar@255:     
alpar@255:   public :
alpar@255:     
marci@459:     Dijkstra(const Graph& _G, const LengthMap& _length) :
alpar@255:       G(_G), length(_length), predecessor(_G), pred_node(_G), distance(_G) { }
alpar@255:     
alpar@255:     void run(Node s);
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@255:     ValueType dist(Node v) const { return distance[v]; }
jacint@373: 
jacint@385:     ///Returns the previous edge of the shortest path tree.
alpar@255: 
jacint@385:     ///For a node \c v it returns the previous edge of the shortest path tree,
jacint@385:     ///i.e. it returns the last edge from a shortest path from the root to \c
jacint@385:     ///v. It is INVALID 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@255:     Edge pred(Node v) const { return predecessor[v]; }
jacint@373: 
jacint@385:     ///Returns the previous node of the shortest path tree.
alpar@255: 
jacint@385:     ///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@255:     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@255:     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@255:     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@255:     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.
jacint@385:     ///\warning the root node is reported to be unreached!
alpar@255:     ///\todo Is this what we want?
alpar@255:     ///\pre \ref run() must be called before using this function.
jacint@385:     ///
alpar@255:     bool reached(Node v) { return G.valid(predecessor[v]); }
alpar@255:     
alpar@255:   };
alpar@255:   
alpar@255: 
alpar@255:   // **********************************************************************
alpar@255:   //  IMPLEMENTATIONS
alpar@255:   // **********************************************************************
alpar@255: 
jacint@385:   ///Runs %Dijkstra algorithm from node the root.
alpar@255: 
jacint@385:   ///This method runs the %Dijkstra algorithm from a root node \c s
jacint@385:   ///in order to
jacint@385:   ///compute the
jacint@385:   ///shortest path to each node. The algorithm computes
jacint@385:   ///- The shortest path tree.
jacint@385:   ///- The distance of each node from the root.
alpar@255:   template <typename Graph, typename LengthMap,
alpar@255: 	    template<class,class,class> class Heap >
alpar@255:   void Dijkstra<Graph,LengthMap,Heap>::run(Node s) {
alpar@255:     
alpar@255:     NodeIt u;
alpar@255:     for ( G.first(u) ; G.valid(u) ; G.next(u) ) {
alpar@255:       predecessor.set(u,INVALID);
alpar@255:       pred_node.set(u,INVALID);
alpar@255:     }
alpar@255:     
marci@433:     typename Graph::template NodeMap<int> heap_map(G,-1);
alpar@255:     
marci@433:     Heap<Node, ValueType, typename Graph::template NodeMap<int> > 
marci@433:       heap(heap_map);
jacint@385:     
alpar@255:     heap.push(s,0); 
alpar@255:     
jacint@385:       while ( !heap.empty() ) {
alpar@255: 	
jacint@385: 	Node v=heap.top(); 
jacint@385: 	ValueType oldvalue=heap[v];
jacint@385: 	heap.pop();
jacint@385: 	distance.set(v, oldvalue);
jacint@385: 	
jacint@385: 	{ //FIXME this bracket is for e to be local
jacint@385: 	  OutEdgeIt e;
jacint@385: 	for(G.first(e, v);
jacint@385: 	    G.valid(e); G.next(e)) {
marci@421: 	  Node w=G.bNode(e); 
alpar@255: 	  
alpar@255: 	  switch(heap.state(w)) {
alpar@255: 	  case heap.PRE_HEAP:
alpar@255: 	    heap.push(w,oldvalue+length[e]); 
alpar@255: 	    predecessor.set(w,e);
alpar@255: 	    pred_node.set(w,v);
alpar@255: 	    break;
alpar@255: 	  case heap.IN_HEAP:
alpar@255: 	    if ( oldvalue+length[e] < heap[w] ) {
alpar@255: 	      heap.decrease(w, oldvalue+length[e]); 
alpar@255: 	      predecessor.set(w,e);
alpar@255: 	      pred_node.set(w,v);
alpar@255: 	    }
alpar@255: 	    break;
alpar@255: 	  case heap.POST_HEAP:
alpar@255: 	    break;
alpar@255: 	  }
alpar@255: 	}
jacint@385:       } //FIXME tis bracket
jacint@385:       }
alpar@255:   }
alpar@430: 
alpar@430: /// @}
alpar@255:   
alpar@255: } //END OF NAMESPACE HUGO
alpar@255: 
alpar@255: #endif
alpar@255: 
alpar@255: