jacint@159: // -*- C++ -*-
jacint@372: 
jacint@159: /* 
jacint@211:  *template <Graph, T, Heap=FibHeap, LengthMap=Graph::EdgeMap<T> >
jacint@159:  *
jacint@159:  *Constructor: 
jacint@159:  *
jacint@211:  *Dijkstra(Graph G, LengthMap length)
jacint@159:  *
jacint@159:  *
jacint@211:  *Methods:
jacint@159:  *
jacint@211:  *void run(Node s)
jacint@159:  *
jacint@211:  *T dist(Node v) : After run(s) was run, it returns the distance from s to v. 
jacint@211:  *   Returns T() if v is not reachable from s.
jacint@159:  *
jacint@211:  *Edge pred(Node v) : After run(s) was run, it returns the last 
jacint@211:  *   edge of a shortest s-v path. It is INVALID for s and for 
jacint@211:  *   the nodes not reachable from s.
jacint@159:  *
jacint@211:  *bool reached(Node v) : After run(s) was run, it is true iff v is 
jacint@211:  *   reachable from s
jacint@159:  *
jacint@159:  */
jacint@159: 
jacint@211: #ifndef HUGO_DIJKSTRA_H
jacint@211: #define HUGO_DIJKSTRA_H
jacint@159: 
jacint@372: ///\file
jacint@372: ///\brief Dijkstra algorithm.
jacint@372: 
jacint@159: #include <fib_heap.h>
jacint@372: #include <bin_heap.h>
jacint@211: #include <invalid.h>
jacint@159: 
jacint@159: namespace hugo {
jacint@211:   
jacint@372:   //Alpar: Changed the order of the parameters
jacint@372:   
jacint@372:   ///%Dijkstra algorithm class.
jacint@372: 
jacint@372:   ///This class provides an efficient implementation of %Dijkstra algorithm.
jacint@372:   ///The edge lengths are passed to the algorithm using a
jacint@372:   ///\ref ReadMapSkeleton "readable map",
jacint@372:   ///so it is easy to change it to any kind of length.
jacint@372:   ///
jacint@372:   ///The type of the length is determined by the \c ValueType of the length map.
jacint@372:   ///
jacint@372:   ///It is also possible to change the underlying priority heap.
jacint@372:   ///
jacint@372:   ///\param Graph The graph type the algorithm runs on.
jacint@372:   ///\param LengthMap This read-only
jacint@372:   ///EdgeMap
jacint@372:   ///determines the
jacint@372:   ///lengths of the edges. It is read once for each edge, so the map
jacint@372:   ///may involve in relatively time consuming process to compute the edge
jacint@372:   ///length if it is necessary. The default map type is
jacint@372:   ///\ref GraphSkeleton::EdgeMap "Graph::EdgeMap<int>"
jacint@372:   ///\param Heap The heap type used by the %Dijkstra
jacint@372:   ///algorithm. The default
jacint@372:   ///is using \ref BinHeap "binary heap".
jacint@372:   
jacint@372: #ifdef DOXYGEN
jacint@372:   template <typename Graph,
jacint@372: 	    typename LengthMap,
jacint@372: 	    typename Heap>
jacint@372: #else
jacint@372:   template <typename Graph,
jacint@372: 	    typename LengthMap=typename Graph::EdgeMap<int>,
jacint@372: 	    template <class,class,class> class Heap = BinHeap >
jacint@372: #endif
jacint@211:   class Dijkstra{
jacint@372:   public:
jacint@211:     typedef typename Graph::Node Node;
jacint@211:     typedef typename Graph::NodeIt NodeIt;
jacint@211:     typedef typename Graph::Edge Edge;
jacint@211:     typedef typename Graph::OutEdgeIt OutEdgeIt;
jacint@211:     
jacint@372:     typedef typename LengthMap::ValueType ValueType;
jacint@372:     typedef typename Graph::NodeMap<Edge> PredMap;
jacint@372:     typedef typename Graph::NodeMap<Node> PredNodeMap;
jacint@372:     typedef typename Graph::NodeMap<ValueType> DistMap;
jacint@372: 
jacint@372:   private:
jacint@211:     const Graph& G;
jacint@211:     const LengthMap& length;
jacint@372:     PredMap predecessor;
jacint@372:     PredNodeMap pred_node;
jacint@372:     DistMap distance;
jacint@211:     
jacint@159:   public :
jacint@211:     
jacint@372:     Dijkstra(Graph& _G, LengthMap& _length) :
jacint@372:       G(_G), length(_length), predecessor(_G), pred_node(_G), distance(_G) { }
jacint@159:     
jacint@372:     void run(Node s);
jacint@372:     
jacint@372:     ///The distance of a node from the source.
jacint@211: 
jacint@372:     ///Returns the distance of a node from the source.
jacint@372:     ///\pre \ref run() must be called before using this function.
jacint@372:     ///\warning If node \c v in unreachable from the source the return value
jacint@372:     ///of this funcion is undefined.
jacint@372:     ValueType dist(Node v) const { return distance[v]; }
jacint@372:     ///Returns the edges of the shortest path tree.
jacint@211: 
jacint@372:     ///For a node \c v it returns the last edge of the shortest path
jacint@372:     ///from the source to \c v or INVALID if \c v is unreachable
jacint@372:     ///from the source.
jacint@372:     ///\pre \ref run() must be called before using this function.
jacint@372:     Edge pred(Node v) const { return predecessor[v]; }
jacint@372:     ///Returns the nodes of the shortest paths.
jacint@211: 
jacint@372:     ///For a node \c v it returns the last but one node of the shortest path
jacint@372:     ///from the source to \c v or INVALID if \c v is unreachable
jacint@372:     ///from the source.
jacint@372:     ///\pre \ref run() must be called before using this function.
jacint@372:     Node predNode(Node v) const { return pred_node[v]; }
jacint@372:     
jacint@372:     ///Returns a reference to the NodeMap of distances.
jacint@372: 
jacint@372:     ///\pre \ref run() must be called before using this function.
jacint@372:     ///
jacint@372:     const DistMap &distMap() const { return distance;}
jacint@372:     ///Returns a reference to the shortest path tree map.
jacint@372: 
jacint@372:     ///Returns a reference to the NodeMap of the edges of the
jacint@372:     ///shortest path tree.
jacint@372:     ///\pre \ref run() must be called before using this function.
jacint@372:     const PredMap &predMap() const { return predecessor;}
jacint@372:     ///Returns a reference to the map of nodes of  shortest paths.
jacint@372: 
jacint@372:     ///Returns a reference to the NodeMap of the last but one nodes of the
jacint@372:     ///shortest paths.
jacint@372:     ///\pre \ref run() must be called before using this function.
jacint@372:     const PredNodeMap &predNodeMap() const { return pred_node;}
jacint@372: 
jacint@372:     ///Checks if a node is reachable from the source.
jacint@372: 
jacint@372:     ///Returns \c true if \c v is reachable from the source.
jacint@372:     ///\warning the source node is reported to be unreached!
jacint@372:     ///\todo Is this what we want?
jacint@372:     ///\pre \ref run() must be called before using this function.
jacint@372:     ///
jacint@372:     bool reached(Node v) { return G.valid(predecessor[v]); }
jacint@372:     
jacint@372:   };
jacint@372:   
jacint@372: 
jacint@372:   // **********************************************************************
jacint@372:   //  IMPLEMENTATIONS
jacint@372:   // **********************************************************************
jacint@372: 
jacint@372:   ///Runs %Dijkstra algorithm from node the source.
jacint@372: 
jacint@372:   ///This method runs the %Dijkstra algorithm from a source node \c s
jacint@372:   ///in order to
jacint@372:   ///compute the
jacint@372:   ///shortest path to each node. The algorithm computes
jacint@372:   ///- The shortest path tree.
jacint@372:   ///- The distance of each node from the source.
jacint@372:   template <typename Graph, typename LengthMap,
jacint@372: 	    template<class,class,class> class Heap >
jacint@372:   void Dijkstra<Graph,LengthMap,Heap>::run(Node s) {
jacint@372:     
jacint@372:     NodeIt u;
jacint@372:     for ( G.first(u) ; G.valid(u) ; G.next(u) ) {
jacint@372:       predecessor.set(u,INVALID);
jacint@372:       pred_node.set(u,INVALID);
jacint@372:       // If a node is unreacheable, then why should be the dist=0?
jacint@372:       // distance.set(u,0);
jacint@372:       //      reach.set(u,false);
jacint@372:     }
jacint@372:     
jacint@372:     typename Graph::NodeMap<int> heap_map(G,-1);
jacint@372:     
jacint@372:     Heap<Node,ValueType,typename Graph::NodeMap<int> > heap(heap_map);
jacint@372:     
jacint@372:     heap.push(s,0); 
jacint@372:     
jacint@211:       while ( !heap.empty() ) {
jacint@159: 	
jacint@211: 	Node v=heap.top(); 
jacint@372: 	ValueType oldvalue=heap[v];
jacint@211: 	heap.pop();
jacint@211: 	distance.set(v, oldvalue);
jacint@372: 	
jacint@372: 	{ //FIXME this bracket is for e to be local
jacint@372: 	  OutEdgeIt e;
jacint@372: 	for(G.first(e, v);
jacint@372: 	    G.valid(e); G.next(e)) {
jacint@211: 	  Node w=G.head(e); 
jacint@372: 	  
jacint@372: 	  switch(heap.state(w)) {
jacint@372: 	  case heap.PRE_HEAP:
jacint@372: 	    heap.push(w,oldvalue+length[e]); 
jacint@372: 	    predecessor.set(w,e);
jacint@372: 	    pred_node.set(w,v);
jacint@372: 	    break;
jacint@372: 	  case heap.IN_HEAP:
jacint@372: 	    if ( oldvalue+length[e] < heap[w] ) {
jacint@372: 	      heap.decrease(w, oldvalue+length[e]); 
jacint@211: 	      predecessor.set(w,e);
jacint@372: 	      pred_node.set(w,v);
jacint@159: 	    }
jacint@372: 	    break;
jacint@372: 	  case heap.POST_HEAP:
jacint@372: 	    break;
jacint@159: 	  }
jacint@159: 	}
jacint@372:       } //FIXME tis bracket
jacint@211:       }
jacint@372:   }
jacint@167:   
jacint@372: } //END OF NAMESPACE HUGO
jacint@159: 
jacint@159: #endif
jacint@159: 
jacint@159: