jacint@33: /*
jacint@33:  *dijkstra
jacint@33:  *by jacint
jacint@33:  *Performs Dijkstra's algorithm from node s. 
jacint@33:  *
jacint@33:  *Constructor: 
jacint@33:  *
jacint@33:  *dijkstra(graph_type& G, node_iterator s, edge_property_vector& distance)
jacint@33:  *
jacint@33:  *
jacint@33:  *
jacint@33:  *Member functions:
jacint@33:  *
jacint@33:  *void run()
jacint@33:  *
jacint@33:  *  The following function should be used after run() was already run.
jacint@33:  *
jacint@33:  *
jacint@33:  *T dist(node_iterator v) : returns the distance from s to v. 
jacint@33:  *   It is 0 if v is not reachable from s.
jacint@33:  *
jacint@33:  *
jacint@33:  *edge_iterator pred(node_iterator v)
jacint@33:  *   Returns the last edge of a shortest s-v path. 
jacint@33:  *   Returns an invalid iterator if v=s or v is not
jacint@33:  *   reachable from s.
jacint@33:  *
jacint@33:  *
jacint@33:  *bool reach(node_iterator v) : true if v is reachable from s
jacint@33:  *
jacint@33:  *
jacint@33:  *
jacint@33:  *
jacint@33:  *
jacint@33:  *Problems: 
jacint@33:  * 
jacint@33:  *Heap implementation is needed, because the priority queue of stl
jacint@33:  *does not have a mathod for key-decrease, so we had to use here a 
jacint@33:  *g\'any solution.
jacint@33:  * 
jacint@33:  *The implementation of infinity would be desirable, see after line 100. 
jacint@33:  */
jacint@33: 
jacint@33: #ifndef DIJKSTRA_HH
jacint@33: #define DIJKSTRA_HH
jacint@33: 
jacint@33: #include <queue>
jacint@33: #include <algorithm>
jacint@33: 
jacint@33: #include <marci_graph_traits.hh>
jacint@33: #include <marci_property_vector.hh>
jacint@33: 
jacint@33: 
jacint@33: namespace std {
jacint@33:   namespace marci {
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33:     template <typename graph_type, typename T>
jacint@33:     class dijkstra{
jacint@33:       typedef typename graph_traits<graph_type>::node_iterator node_iterator;
jacint@33:       typedef typename graph_traits<graph_type>::edge_iterator edge_iterator;
jacint@33:       typedef typename graph_traits<graph_type>::each_node_iterator each_node_iterator;
jacint@33:       typedef typename graph_traits<graph_type>::in_edge_iterator in_edge_iterator;
jacint@33:       typedef typename graph_traits<graph_type>::out_edge_iterator out_edge_iterator;
jacint@33:       
jacint@33:       
jacint@33:       graph_type& G;
jacint@33:       node_iterator s;
jacint@33:       node_property_vector<graph_type, edge_iterator> predecessor;
jacint@33:       node_property_vector<graph_type, T> distance;
jacint@33:       edge_property_vector<graph_type, T> length;
jacint@33:       node_property_vector<graph_type, bool> reached;
jacint@33:           
jacint@33:   public :
jacint@33: 
jacint@33:     /*
jacint@33:       The distance of all the nodes is 0.
jacint@33:     */
jacint@33:     dijkstra(graph_type& _G, node_iterator _s, edge_property_vector<graph_type, T>& _length) : 
jacint@33:       G(_G), s(_s), predecessor(G, 0), distance(G, 0), length(_length), reached(G, false) { }
jacint@33:     
jacint@33: 
jacint@33:       
jacint@33:       /*By Misi.*/
jacint@33:       struct node_dist_comp
jacint@33:       {
jacint@33: 	node_property_vector<graph_type, T> &d;
jacint@33: 	node_dist_comp(node_property_vector<graph_type, T> &_d) : d(_d) {} 
jacint@33: 	
jacint@33: 	bool operator()(const node_iterator& u, const node_iterator& v) const 
jacint@33: 	{ return d.get(u) < d.get(v); }
jacint@33:       };
jacint@33: 
jacint@33: 
jacint@33:       
jacint@33:       void run() {
jacint@33: 	
jacint@33: 	node_property_vector<graph_type, bool> scanned(G, false);
jacint@33: 	std::priority_queue<node_iterator, vector<node_iterator>, node_dist_comp> 
jacint@33: 	  heap(( node_dist_comp(distance) ));
jacint@33:       
jacint@33: 	heap.push(s);
jacint@33: 	reached.put(s, true);
jacint@33: 
jacint@33: 	while (!heap.empty()) {
jacint@33: 
jacint@33: 	  node_iterator v=heap.top();	
jacint@33: 	  heap.pop();
jacint@33: 
jacint@33: 
jacint@33: 	  if (!scanned.get(v)) {
jacint@33: 	
jacint@33: 	    for(out_edge_iterator e=G.first_out_edge(v); e.valid(); ++e) {
jacint@33: 	      node_iterator w=G.head(e);
jacint@33: 
jacint@33: 	      if (!scanned.get(w)) {
jacint@33: 		if (!reached.get(w)) {
jacint@33: 		  reached.put(w,true);
jacint@33: 		  distance.put(w, distance.get(v)-length.get(e));
jacint@33: 		  predecessor.put(w,e);
jacint@33: 		} else if (distance.get(v)-length.get(e)>distance.get(w)) {
jacint@33: 		  distance.put(w, distance.get(v)-length.get(e));
jacint@33: 		  predecessor.put(w,e);
jacint@33: 		}
jacint@33: 		
jacint@33: 		heap.push(w);
jacint@33: 	      
jacint@33: 	      } 
jacint@33: 
jacint@33: 	    } 
jacint@33: 	    scanned.put(v,true);
jacint@33: 	    
jacint@33: 	  } // if (!scanned.get(v))
jacint@33: 	  
jacint@33: 	  
jacint@33: 	  
jacint@33: 	} // while (!heap.empty())
jacint@33: 
jacint@33: 	
jacint@33:       } //void run()
jacint@33:       
jacint@33:       
jacint@33:       
jacint@33: 
jacint@33: 
jacint@33:       /*
jacint@33:        *Returns the distance of the node v.
jacint@33:        *It is 0 for the root and for the nodes not
jacint@33:        *reachable form the root.
jacint@33:        */      
jacint@33:       T dist(node_iterator v) {
jacint@33: 	return -distance.get(v);
jacint@33:       }
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33:       /*
jacint@33:        *  Returns the last edge of a shortest s-v path. 
jacint@33:        *  Returns an invalid iterator if v=root or v is not
jacint@33:        *  reachable from the root.
jacint@33:        */      
jacint@33:       edge_iterator pred(node_iterator v) {
jacint@33: 	if (v!=s) { return predecessor.get(v);}
jacint@33: 	else {return edge_iterator();}
jacint@33:       }
jacint@33:      
jacint@33: 
jacint@33:       
jacint@33:       bool reach(node_iterator v) {
jacint@33: 	return reached.get(v);
jacint@33:       }
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33:     };// class dijkstra
jacint@33: 
jacint@33: 
jacint@33: 
jacint@33:   } // namespace marci
jacint@33: }
jacint@33: #endif //DIJKSTRA_HH
jacint@33: 
jacint@33: