[Lemon-commits] [lemon_svn] jacint: r65 - in hugo/trunk/src/work: . jacint

[Lemon SVN]

Author: jacint
Date: Fri Jan 30 15:56:11 2004
New Revision: 65

Added:
   hugo/trunk/src/work/jacint/dijkstra.hh
   hugo/trunk/src/work/jacint/reverse_bfs.hh
Removed:
   hugo/trunk/src/work/dijkstra.hh
   hugo/trunk/src/work/preflow_push_hl.hh
   hugo/trunk/src/work/preflow_push_max_flow.hh
   hugo/trunk/src/work/reverse_bfs.hh

Log:
*** empty log message ***


Added: hugo/trunk/src/work/jacint/dijkstra.hh
==============================================================================
--- (empty file)
+++ hugo/trunk/src/work/jacint/dijkstra.hh	Fri Jan 30 15:56:11 2004
@@ -0,0 +1,192 @@
+/*
+ *dijkstra
+ *by jacint
+ *Performs Dijkstra's algorithm from node s. 
+ *
+ *Constructor: 
+ *
+ *dijkstra(graph_type& G, node_iterator s, edge_property_vector& distance)
+ *
+ *
+ *
+ *Member functions:
+ *
+ *void run()
+ *
+ *  The following function should be used after run() was already run.
+ *
+ *
+ *T dist(node_iterator v) : returns the distance from s to v. 
+ *   It is 0 if v is not reachable from s.
+ *
+ *
+ *edge_iterator pred(node_iterator v)
+ *   Returns the last edge of a shortest s-v path. 
+ *   Returns an invalid iterator if v=s or v is not
+ *   reachable from s.
+ *
+ *
+ *bool reach(node_iterator v) : true if v is reachable from s
+ *
+ *
+ *
+ *
+ *
+ *Problems: 
+ * 
+ *Heap implementation is needed, because the priority queue of stl
+ *does not have a mathod for key-decrease, so we had to use here a 
+ *g\'any solution.
+ * 
+ *The implementation of infinity would be desirable, see after line 100. 
+ */
+
+#ifndef DIJKSTRA_HH
+#define DIJKSTRA_HH
+
+#include <queue>
+#include <algorithm>
+
+#include <marci_graph_traits.hh>
+#include <marci_property_vector.hh>
+
+
+namespace std {
+  namespace marci {
+
+
+
+
+
+    template <typename graph_type, typename T>
+    class dijkstra{
+      typedef typename graph_traits<graph_type>::node_iterator node_iterator;
+      typedef typename graph_traits<graph_type>::edge_iterator edge_iterator;
+      typedef typename graph_traits<graph_type>::each_node_iterator each_node_iterator;
+      typedef typename graph_traits<graph_type>::in_edge_iterator in_edge_iterator;
+      typedef typename graph_traits<graph_type>::out_edge_iterator out_edge_iterator;
+      
+      
+      graph_type& G;
+      node_iterator s;
+      node_property_vector<graph_type, edge_iterator> predecessor;
+      node_property_vector<graph_type, T> distance;
+      edge_property_vector<graph_type, T> length;
+      node_property_vector<graph_type, bool> reached;
+          
+  public :
+
+    /*
+      The distance of all the nodes is 0.
+    */
+    dijkstra(graph_type& _G, node_iterator _s, edge_property_vector<graph_type, T>& _length) : 
+      G(_G), s(_s), predecessor(G, 0), distance(G, 0), length(_length), reached(G, false) { }
+    
+
+      
+      /*By Misi.*/
+      struct node_dist_comp
+      {
+	node_property_vector<graph_type, T> &d;
+	node_dist_comp(node_property_vector<graph_type, T> &_d) : d(_d) {} 
+	
+	bool operator()(const node_iterator& u, const node_iterator& v) const 
+	{ return d.get(u) < d.get(v); }
+      };
+
+
+      
+      void run() {
+	
+	node_property_vector<graph_type, bool> scanned(G, false);
+	std::priority_queue<node_iterator, vector<node_iterator>, node_dist_comp> 
+	  heap(( node_dist_comp(distance) ));
+      
+	heap.push(s);
+	reached.put(s, true);
+
+	while (!heap.empty()) {
+
+	  node_iterator v=heap.top();	
+	  heap.pop();
+
+
+	  if (!scanned.get(v)) {
+	
+	    for(out_edge_iterator e=G.first_out_edge(v); e.valid(); ++e) {
+	      node_iterator w=G.head(e);
+
+	      if (!scanned.get(w)) {
+		if (!reached.get(w)) {
+		  reached.put(w,true);
+		  distance.put(w, distance.get(v)-length.get(e));
+		  predecessor.put(w,e);
+		} else if (distance.get(v)-length.get(e)>distance.get(w)) {
+		  distance.put(w, distance.get(v)-length.get(e));
+		  predecessor.put(w,e);
+		}
+		
+		heap.push(w);
+	      
+	      } 
+
+	    } 
+	    scanned.put(v,true);
+	    
+	  } // if (!scanned.get(v))
+	  
+	  
+	  
+	} // while (!heap.empty())
+
+	
+      } //void run()
+      
+      
+      
+
+
+      /*
+       *Returns the distance of the node v.
+       *It is 0 for the root and for the nodes not
+       *reachable form the root.
+       */      
+      T dist(node_iterator v) {
+	return -distance.get(v);
+      }
+
+
+
+      /*
+       *  Returns the last edge of a shortest s-v path. 
+       *  Returns an invalid iterator if v=root or v is not
+       *  reachable from the root.
+       */      
+      edge_iterator pred(node_iterator v) {
+	if (v!=s) { return predecessor.get(v);}
+	else {return edge_iterator();}
+      }
+     
+
+      
+      bool reach(node_iterator v) {
+	return reached.get(v);
+      }
+
+
+
+
+
+
+
+
+
+    };// class dijkstra
+
+
+
+  } // namespace marci
+}
+#endif //DIJKSTRA_HH
+
+

Added: hugo/trunk/src/work/jacint/reverse_bfs.hh
==============================================================================
--- (empty file)
+++ hugo/trunk/src/work/jacint/reverse_bfs.hh	Fri Jan 30 15:56:11 2004
@@ -0,0 +1,94 @@
+/*
+reverse_bfs
+by jacint
+Performs a bfs on the out edges. It does not count predecessors, 
+only the distances, but one can easily modify it to know the pred as well.
+
+Constructor: 
+
+reverse_bfs(graph_type& G, node_iterator t)
+
+
+
+Member functions:
+
+void run(): runs a reverse bfs from t
+
+  The following function should be used after run() was already run.
+
+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.
+
+*/
+#ifndef REVERSE_BFS_HH
+#define REVERSE_BFS_HH
+
+#include <queue>
+
+#include <marci_graph_traits.hh>
+#include <marci_property_vector.hh>
+
+
+
+namespace  marci {
+
+  template <typename graph_type>
+  class reverse_bfs {
+    typedef typename graph_traits<graph_type>::node_iterator node_iterator;
+    //typedef typename graph_traits<graph_type>::edge_iterator edge_iterator;
+    typedef typename graph_traits<graph_type>::each_node_iterator each_node_iterator;
+    typedef typename graph_traits<graph_type>::in_edge_iterator in_edge_iterator;
+
+
+    graph_type& G;
+    node_iterator t;
+//    node_property_vector<graph_type, edge_iterator> pred;
+    node_property_vector<graph_type, int> distance;
+    
+
+  public :
+
+    /*
+      The distance of the nodes is n, except t for which it is 0.
+    */
+    reverse_bfs(graph_type& _G, node_iterator _t) : G(_G), t(_t), distance(G, number_of(G.first_node())) {
+      distance.put(t,0);
+    }
+    
+    void run() {
+
+      node_property_vector<graph_type, bool> reached(G, false); 
+      reached.put(t, true);
+
+      std::queue<node_iterator> bfs_queue;
+      bfs_queue.push(t);
+
+      while (!bfs_queue.empty()) {
+
+        node_iterator v=bfs_queue.front();	
+	bfs_queue.pop();
+
+	for(in_edge_iterator e=G.first_in_edge(v); e.valid(); ++e) {
+	  node_iterator w=G.tail(e);
+	  if (!reached.get(w)) {
+	    bfs_queue.push(w);
+	    distance.put(w, distance.get(v)+1);
+	    reached.put(w, true);
+	  }
+	}
+      }
+    }
+
+
+
+    int dist(node_iterator v) {
+      return distance.get(v);
+    }
+
+
+  };
+
+} // namespace marci
+
+#endif //REVERSE_BFS_HH
+
+