athos@77: /*
athos@77: reverse_bfs
athos@77: by jacint
athos@77: Performs a bfs on the out edges. It does not count predecessors, 
athos@77: only the distances, but one can easily modify it to know the pred as well.
athos@77: 
athos@77: Constructor: 
athos@77: 
athos@77: reverse_bfs(graph_type& G, node_iterator t)
athos@77: 
athos@77: 
athos@77: 
athos@77: Member functions:
athos@77: 
athos@77: void run(): runs a reverse bfs from t
athos@77: 
athos@77:   The following function should be used after run() was already run.
athos@77: 
athos@77: int dist(node_iterator v) : returns the distance from v to t. It is the number of nodes if t is not reachable from v.
athos@77: 
athos@77: */
athos@77: #ifndef REVERSE_BFS_HH
athos@77: #define REVERSE_BFS_HH
athos@77: 
athos@77: #include <queue>
athos@77: 
athos@77: //#include <marci_list_graph.hh>
athos@77: //#include <marci_property_vector.hh>
athos@77: 
athos@77: 
athos@77: 
athos@120: namespace  hugo {
athos@77: 
athos@77:   template <typename graph_type>
athos@77:   class reverse_bfs {
athos@77: 
athos@77:     typedef typename graph_type::NodeIt NodeIt;
athos@77:     typedef typename graph_type::EdgeIt EdgeIt;
athos@77:     typedef typename graph_type::EachNodeIt EachNodeIt;
athos@77:     typedef typename graph_type::EachEdgeIt EachEdgeIt;
athos@77:     typedef typename graph_type::OutEdgeIt OutEdgeIt;
athos@77:     typedef typename graph_type::InEdgeIt InEdgeIt;
athos@77:     typedef typename graph_type::SymEdgeIt SymEdgeIt;
athos@77: 
athos@77: 
athos@77: 
athos@77:     graph_type& G;
athos@77:     NodeIt t;
athos@77: //    node_property_vector<graph_type, edge_iterator> pred;
athos@77:     //node_property_vector<graph_type, int>
athos@77:     typename graph_type::NodeMap<int> distance;
athos@77:     
athos@77: 
athos@77:   public :
athos@77: 
athos@77:     /*
athos@77:       The distance of the nodes is n, except t for which it is 0.
athos@77:     */
athos@77:     reverse_bfs(graph_type& _G, NodeIt _t) : 
athos@77:       G(_G), t(_t), 
athos@77:       distance(G, G.nodeNum()) {
athos@77:       distance.set(t,0);
athos@77:     }
athos@77:     
athos@77:     void run() {
athos@77: 
athos@77:       //node_property_vector<graph_type, bool> 
athos@77:       typename graph_type::NodeMap<bool> reached(G, false); 
athos@77:       reached.set(t, true);
athos@77: 
athos@77:       std::queue<NodeIt> bfs_queue;
athos@77:       bfs_queue.push(t);
athos@77: 
athos@77:       while (!bfs_queue.empty()) {
athos@77: 
athos@77:         NodeIt v=bfs_queue.front();	
athos@77: 	bfs_queue.pop();
athos@77: 
athos@77: 	for(InEdgeIt e=G.template first<InEdgeIt>(v); e.valid(); ++e) {
athos@77: 	  NodeIt w=G.tail(e);
athos@77: 	  if (!reached.get(w)) {
athos@77: 	    bfs_queue.push(w);
athos@77: 	    distance.set(w, distance.get(v)+1);
athos@77: 	    reached.set(w, true);
athos@77: 	  }
athos@77: 	}
athos@77:       }
athos@77:     }
athos@77: 
athos@77: 
athos@77: 
athos@77:     int dist(NodeIt v) {
athos@77:       return distance.get(v);
athos@77:     }
athos@77: 
athos@77: 
athos@77:   };
athos@77: 
alpar@105: } // namespace hugo
athos@77: 
athos@77: #endif //REVERSE_BFS_HH
athos@77: 
athos@77: