alpar@222: // -*- C++ -*-
alpar@222: /* 
alpar@222:  *template <Graph, T, Heap=FibHeap, LengthMap=Graph::EdgeMap<T> >
alpar@222:  *
alpar@222:  *Constructor: 
alpar@222:  *
alpar@222:  *Dijkstra(Graph G, LengthMap length)
alpar@222:  *
alpar@222:  *
alpar@222:  *Methods:
alpar@222:  *
alpar@222:  *void run(Node s)
alpar@222:  *
alpar@222:  *T dist(Node v) : After run(s) was run, it returns the distance from s to v. 
alpar@222:  *   Returns T() if v is not reachable from s.
alpar@222:  *
alpar@222:  *Edge pred(Node v) : After run(s) was run, it returns the last 
alpar@222:  *   edge of a shortest s-v path. It is INVALID for s and for 
alpar@222:  *   the nodes not reachable from s.
alpar@222:  *
alpar@222:  *bool reached(Node v) : After run(s) was run, it is true iff v is 
alpar@222:  *   reachable from s
alpar@222:  *
alpar@222:  */
alpar@222: 
alpar@222: #ifndef HUGO_DIJKSTRA_H
alpar@222: #define HUGO_DIJKSTRA_H
alpar@222: 
alpar@222: #include <fib_heap.h>
alpar@222: #include <invalid.h>
alpar@222: 
alpar@222: namespace hugo {
alpar@222:   
alpar@222:   //Alpar: Changed the order of the parameters
alpar@222:   template <typename Graph,
alpar@222: 	    typename LengthMap=typename Graph::EdgeMap<int>,
alpar@222: 	    typename Heap=FibHeap<typename Graph::Node,
alpar@222: 				  typename LengthMap::ValueType, 
alpar@222: 				  typename Graph::NodeMap<int> > >
alpar@222:   class Dijkstra{
alpar@222:   public:
alpar@222:     typedef typename LengthMap::ValueType ValueType;
alpar@222: 
alpar@222:   private:
alpar@222:     typedef typename Graph::Node Node;
alpar@222:     typedef typename Graph::NodeIt NodeIt;
alpar@222:     typedef typename Graph::Edge Edge;
alpar@222:     typedef typename Graph::OutEdgeIt OutEdgeIt;
alpar@222:     
alpar@222:     const Graph& G;
alpar@222:     const LengthMap& length;
alpar@222:     typedef typename Graph::NodeMap<Edge> PredMap;
alpar@222:     PredMap predecessor;
alpar@222:     //In place of reach:
alpar@222:     typedef typename Graph::NodeMap<Node> PredNodeMap;
alpar@222:     PredNodeMap pred_node;
alpar@222:     typedef typename Graph::NodeMap<ValueType> DistMap;
alpar@222:     DistMap distance;
alpar@222:     //I don't like this:
alpar@222:     //     //FIXME:
alpar@222:     //     typename Graph::NodeMap<bool> reach;
alpar@222:     //     //typename Graph::NodeMap<int> reach;
alpar@222:     
alpar@222:   public :
alpar@222:     
alpar@222:     /*
alpar@222:       The distance of the nodes is 0.
alpar@222:     */
alpar@222:     Dijkstra(Graph& _G, LengthMap& _length) :
alpar@222:       G(_G), length(_length), predecessor(_G), pred_node(_G), distance(_G) { }
alpar@222:     
alpar@222: 
alpar@222:     void run(Node s);
alpar@222:     
alpar@222:     ValueType dist(Node v) const { return distance[v]; }
alpar@222:     Edge pred(Node v) const { return predecessor[v]; }
alpar@222:     Node predNode(Node v) const { return pred_node[v]; }
alpar@222:     
alpar@222:     const DistMap &distMap() const { return distance;}
alpar@222:     const PredMap &predMap() const { return predecessor;}
alpar@222:     const PredNodeMap &predNodeMap() const { return pred_node;}
alpar@222: 
alpar@222:     //    bool reached(Node v) { return reach[v]; }
alpar@222:     ///\warning \c s is not reached!
alpar@222:     ///
alpar@222:     bool reached(Node v) { return G.valid(predecessor[v]); }
alpar@222:     
alpar@222:   };
alpar@222:   
alpar@222: 
alpar@222:   // IMPLEMENTATIONS
alpar@222: 
alpar@222:   template <typename Graph, typename LengthMap, typename Heap >
alpar@222:   void Dijkstra<Graph,LengthMap,Heap>::run(Node s) {
alpar@222:     
alpar@222:     NodeIt u;
alpar@222:     for ( G.first(u) ; G.valid(u) ; G.next(u) ) {
alpar@222:       predecessor.set(u,INVALID);
alpar@222:       // If a node is unreacheable, then why should be the dist=0?
alpar@222:       // distance.set(u,0);
alpar@222:       //      reach.set(u,false);
alpar@222:     }
alpar@222:     
alpar@222:     //We don't need it at all.
alpar@222:     //     //FIXME:
alpar@222:     //     typename Graph::NodeMap<bool> scanned(G,false);
alpar@222:     //     //typename Graph::NodeMap<int> scanned(G,false);
alpar@222:     typename Graph::NodeMap<int> heap_map(G,-1);
alpar@222:     
alpar@222:     Heap heap(heap_map);
alpar@222:     
alpar@222:     heap.push(s,0); 
alpar@222:     //    reach.set(s, true);
alpar@222:     
alpar@222:       while ( !heap.empty() ) {
alpar@222: 	
alpar@222: 	Node v=heap.top(); 
alpar@222: 	ValueType oldvalue=heap[v];
alpar@222: 	heap.pop();
alpar@222: 	distance.set(v, oldvalue);
alpar@222: 	
alpar@222: 	for(OutEdgeIt e(G,v); G.valid(e); G.next(e)) {
alpar@222: 	  Node w=G.head(e); 
alpar@222: 	  
alpar@222: 	  switch(heap.state(w)) {
alpar@222: 	  case Heap::PRE_HEAP:
alpar@222: 	    //	    reach.set(w,true);
alpar@222: 	    heap.push(w,oldvalue+length[e]); 
alpar@222: 	    predecessor.set(w,e);
alpar@222: 	    pred_node.set(w,v);
alpar@222: 	    break;
alpar@222: 	  case Heap::IN_HEAP:
alpar@222: 	    if ( oldvalue+length[e] < heap[w] ) {
alpar@222: 	      heap.decrease(w, oldvalue+length[e]); 
alpar@222: 	      predecessor.set(w,e);
alpar@222: 	      pred_node.set(w,v);
alpar@222: 	    }
alpar@222: 	    break;
alpar@222: 	  case Heap::POST_HEAP:
alpar@222: 	    break;
alpar@222: 	  }
alpar@222: 	}
alpar@222:       }
alpar@222:   }
alpar@222:   
alpar@222: } //END OF NAMESPACE HUGO
alpar@222: 
alpar@222: #endif
alpar@222: 
alpar@222: