jacint@50: /*
jacint@50:  *dijkstra
jacint@50:  *by jacint
jacint@78:  *Performs Dijkstra's algorithm from Node s. 
jacint@50:  *
jacint@50:  *Constructor: 
jacint@50:  *
jacint@78:  *dijkstra(graph_type& G, NodeIt s, EdgeMap& distance)
jacint@50:  *
jacint@50:  *
jacint@50:  *
jacint@50:  *Member functions:
jacint@50:  *
jacint@50:  *void run()
jacint@50:  *
jacint@50:  *  The following function should be used after run() was already run.
jacint@50:  *
jacint@50:  *
jacint@78:  *T dist(NodeIt v) : returns the distance from s to v. 
jacint@50:  *   It is 0 if v is not reachable from s.
jacint@50:  *
jacint@50:  *
jacint@78:  *EdgeIt pred(NodeIt v)
jacint@78:  *   Returns the last Edge of a shortest s-v path. 
jacint@50:  *   Returns an invalid iterator if v=s or v is not
jacint@50:  *   reachable from s.
jacint@50:  *
jacint@50:  *
jacint@78:  *bool reach(NodeIt v) : true if v is reachable from s
jacint@50:  *
jacint@50:  *
jacint@50:  *
jacint@50:  *
jacint@50:  *
jacint@50:  *Problems: 
jacint@50:  * 
jacint@50:  *Heap implementation is needed, because the priority queue of stl
jacint@50:  *does not have a mathod for key-decrease, so we had to use here a 
jacint@50:  *g\'any solution.
jacint@50:  * 
jacint@50:  *The implementation of infinity would be desirable, see after line 100. 
jacint@50:  */
jacint@50: 
jacint@50: #ifndef DIJKSTRA_HH
jacint@50: #define DIJKSTRA_HH
jacint@50: 
jacint@50: #include <queue>
jacint@50: #include <algorithm>
jacint@50: 
jacint@50: #include <marci_graph_traits.hh>
jacint@78: #include <marciMap.hh>
jacint@50: 
jacint@50: 
jacint@50: namespace std {
jacint@50:   namespace marci {
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50:     template <typename graph_type, typename T>
jacint@50:     class dijkstra{
jacint@78:       typedef typename graph_traits<graph_type>::NodeIt NodeIt;
jacint@78:       typedef typename graph_traits<graph_type>::EdgeIt EdgeIt;
jacint@78:       typedef typename graph_traits<graph_type>::EachNodeIt EachNodeIt;
jacint@78:       typedef typename graph_traits<graph_type>::InEdgeIt InEdgeIt;
jacint@78:       typedef typename graph_traits<graph_type>::OutEdgeIt OutEdgeIt;
jacint@50:       
jacint@50:       
jacint@50:       graph_type& G;
jacint@78:       NodeIt s;
jacint@78:       NodeMap<graph_type, EdgeIt> predecessor;
jacint@78:       NodeMap<graph_type, T> distance;
jacint@78:       EdgeMap<graph_type, T> length;
jacint@78:       NodeMap<graph_type, bool> reached;
jacint@50:           
jacint@50:   public :
jacint@50: 
jacint@50:     /*
jacint@78:       The distance of all the Nodes is 0.
jacint@50:     */
jacint@78:     dijkstra(graph_type& _G, NodeIt _s, EdgeMap<graph_type, T>& _length) : 
jacint@50:       G(_G), s(_s), predecessor(G, 0), distance(G, 0), length(_length), reached(G, false) { }
jacint@50:     
jacint@50: 
jacint@50:       
jacint@50:       /*By Misi.*/
jacint@78:       struct Node_dist_comp
jacint@50:       {
jacint@78: 	NodeMap<graph_type, T> &d;
jacint@78: 	Node_dist_comp(NodeMap<graph_type, T> &_d) : d(_d) {} 
jacint@50: 	
jacint@78: 	bool operator()(const NodeIt& u, const NodeIt& v) const 
jacint@50: 	{ return d.get(u) < d.get(v); }
jacint@50:       };
jacint@50: 
jacint@50: 
jacint@50:       
jacint@50:       void run() {
jacint@50: 	
jacint@78: 	NodeMap<graph_type, bool> scanned(G, false);
jacint@78: 	std::priority_queue<NodeIt, vector<NodeIt>, Node_dist_comp> 
jacint@78: 	  heap(( Node_dist_comp(distance) ));
jacint@50:       
jacint@50: 	heap.push(s);
jacint@50: 	reached.put(s, true);
jacint@50: 
jacint@50: 	while (!heap.empty()) {
jacint@50: 
jacint@78: 	  NodeIt v=heap.top();	
jacint@50: 	  heap.pop();
jacint@50: 
jacint@50: 
jacint@50: 	  if (!scanned.get(v)) {
jacint@50: 	
jacint@78: 	    for(OutEdgeIt e=G.template first<OutEdgeIt>(v); e.valid(); ++e) {
jacint@78: 	      NodeIt w=G.head(e);
jacint@50: 
jacint@50: 	      if (!scanned.get(w)) {
jacint@50: 		if (!reached.get(w)) {
jacint@50: 		  reached.put(w,true);
jacint@50: 		  distance.put(w, distance.get(v)-length.get(e));
jacint@50: 		  predecessor.put(w,e);
jacint@50: 		} else if (distance.get(v)-length.get(e)>distance.get(w)) {
jacint@50: 		  distance.put(w, distance.get(v)-length.get(e));
jacint@50: 		  predecessor.put(w,e);
jacint@50: 		}
jacint@50: 		
jacint@50: 		heap.push(w);
jacint@50: 	      
jacint@50: 	      } 
jacint@50: 
jacint@50: 	    } 
jacint@50: 	    scanned.put(v,true);
jacint@50: 	    
jacint@50: 	  } // if (!scanned.get(v))
jacint@50: 	  
jacint@50: 	  
jacint@50: 	  
jacint@50: 	} // while (!heap.empty())
jacint@50: 
jacint@50: 	
jacint@50:       } //void run()
jacint@50:       
jacint@50:       
jacint@50:       
jacint@50: 
jacint@50: 
jacint@50:       /*
jacint@78:        *Returns the distance of the Node v.
jacint@78:        *It is 0 for the root and for the Nodes not
jacint@50:        *reachable form the root.
jacint@50:        */      
jacint@78:       T dist(NodeIt v) {
jacint@50: 	return -distance.get(v);
jacint@50:       }
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50:       /*
jacint@78:        *  Returns the last Edge of a shortest s-v path. 
jacint@50:        *  Returns an invalid iterator if v=root or v is not
jacint@50:        *  reachable from the root.
jacint@50:        */      
jacint@78:       EdgeIt pred(NodeIt v) {
jacint@50: 	if (v!=s) { return predecessor.get(v);}
jacint@78: 	else {return EdgeIt();}
jacint@50:       }
jacint@50:      
jacint@50: 
jacint@50:       
jacint@78:       bool reach(NodeIt v) {
jacint@50: 	return reached.get(v);
jacint@50:       }
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50:     };// class dijkstra
jacint@50: 
jacint@50: 
jacint@50: 
jacint@50:   } // namespace marci
jacint@50: }
jacint@50: #endif //DIJKSTRA_HH
jacint@50: 
jacint@50: