alpar@255: // -*- C++ -*-
alpar@255: 
alpar@255: #ifndef HUGO_DIJKSTRA_H
alpar@255: #define HUGO_DIJKSTRA_H
alpar@255: 
alpar@255: ///\file
alpar@255: ///\brief Dijkstra algorithm.
alpar@255: 
alpar@257: #include <fib_heap.h>
klao@258: #include <bin_heap.h>
alpar@257: #include <invalid.h>
alpar@255: 
alpar@255: namespace hugo {
alpar@255:   
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@373:   ///\param Graph The graph type the algorithm runs on.  
jacint@373:   ///\param LengthMap This read-only EdgeMap determines the lengths of
jacint@373:   ///the edges. It is read once for each edge, so the map may involve
jacint@373:   ///in relatively time consuming process to compute the edge length
jacint@373:   ///if it is necessary. The default map type is \ref
jacint@373:   ///GraphSkeleton::EdgeMap "Graph::EdgeMap<int>"
jacint@373:   ///\param Heap The heap type used by the %Dijkstra algorithm. The
jacint@373:   ///default is using \ref BinHeap "binary heap".
alpar@255:   
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,
alpar@255: 	    typename LengthMap=typename Graph::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;
alpar@255:     typedef typename Graph::NodeMap<Edge> PredMap;
alpar@255:     typedef typename Graph::NodeMap<Node> PredNodeMap;
alpar@255:     typedef typename Graph::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:     
alpar@255:     Dijkstra(Graph& _G, 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:     
alpar@255:     ///The distance of a node from the source.
alpar@255: 
alpar@255:     ///Returns the distance of a node from the source.
alpar@255:     ///\pre \ref run() must be called before using this function.
alpar@255:     ///\warning If node \c v in unreachable from the source the return value
alpar@255:     ///of this funcion is undefined.
alpar@255:     ValueType dist(Node v) const { return distance[v]; }
jacint@373: 
alpar@255:     ///Returns the edges of the shortest path tree.
alpar@255: 
alpar@255:     ///For a node \c v it returns the last edge of the shortest path
alpar@255:     ///from the source to \c v or INVALID if \c v is unreachable
alpar@255:     ///from the source.
alpar@255:     ///\pre \ref run() must be called before using this function.
alpar@255:     Edge pred(Node v) const { return predecessor[v]; }
jacint@373: 
alpar@255:     ///Returns the nodes of the shortest paths.
alpar@255: 
alpar@255:     ///For a node \c v it returns the last but one node of the shortest path
alpar@255:     ///from the source to \c v or INVALID if \c v is unreachable
alpar@255:     ///from the source.
alpar@255:     ///\pre \ref run() must be called before 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: 
alpar@255:     ///\pre \ref run() must be called before using this function.
alpar@255:     ///
alpar@255:     const DistMap &distMap() const { return distance;}
jacint@373:     
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@373:     
alpar@255:     ///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
alpar@255:     ///shortest paths.
alpar@255:     ///\pre \ref run() must be called before using this function.
alpar@255:     const PredNodeMap &predNodeMap() const { return pred_node;}
alpar@255: 
alpar@255:     ///Checks if a node is reachable from the source.
alpar@255: 
alpar@255:     ///Returns \c true if \c v is reachable from the source.
alpar@255:     ///\warning the source 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.
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@373:   ///Runs %Dijkstra algorithm from source node \c s.
alpar@255: 
alpar@255:   ///This method runs the %Dijkstra algorithm from a source node \c s
jacint@373:   ///in order to compute the shortest path to each node. The algorithm
jacint@373:   ///computes - The shortest path tree.  - The distance of each node
jacint@373:   ///from the source.
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:     
alpar@255:     typename Graph::NodeMap<int> heap_map(G,-1);
alpar@255:     
alpar@255:     Heap<Node,ValueType,typename Graph::NodeMap<int> > heap(heap_map);
alpar@255:     heap.push(s,0); 
alpar@255:     
jacint@373:     while ( !heap.empty() ) {
jacint@373:       
jacint@373:       Node v=heap.top(); 
jacint@373:       ValueType oldvalue=heap[v];
jacint@373:       heap.pop();
jacint@373:       distance.set(v, oldvalue);
alpar@255: 	
jacint@373:       { //FIXME this bracket is for e to be local
jacint@373: 	OutEdgeIt e;
jacint@373: 	for(G.first(e, v); G.valid(e); G.next(e)) {
alpar@255: 	  Node w=G.head(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@373:       } //FIXME this bracket
jacint@373:     }
alpar@255:   }
alpar@255:   
alpar@255: } //END OF NAMESPACE HUGO
alpar@255: 
alpar@255: #endif
alpar@255: 
alpar@255: