Changeset 286:da414906fe21 in lemon for lemon/dijkstra.h

Timestamp:

09/26/08 12:40:11 (16 years ago)

Author:

Peter Kovacs <kpeter@…>

Branch:

default

Phase:

public

Message:

Improvements related to BFS/DFS/Dijkstra (ticket #96)

• Add run(s,t) function to BfsVisit?.
• Modify run(s,t) functions in the class interfaces to return bool value.
• Bug fix in Dijkstra::start(t) function.
• Improve Dijkstra::currentDist().
• Extend test files to check named class template parameters.
• Doc improvements.

File:

• lemon/dijkstra.h (modified) (6 diffs)

lemon/dijkstra.h

@@ -729 +729 @@
     }
 
-    ///Executes the algorithm until the given target node is reached.
-
-    ///Executes the algorithm until the given target node is reached.
+    ///Executes the algorithm until the given target node is processed.
+
+    ///Executes the algorithm until the given target node is processed.
     ///
     ///This method runs the %Dijkstra algorithm from the root node(s)
-    ///in order to compute the shortest path to \c dest.
+    ///in order to compute the shortest path to \c t.
     ///
     ///The algorithm computes
-    ///- the shortest path to \c dest,
-    ///- the distance of \c dest from the root(s).
+    ///- the shortest path to \c t,
+    ///- the distance of \c t from the root(s).
     ///
     ///\pre init() must be called and at least one root node should be
     ///added with addSource() before using this function.
-    void start(Node dest)
-    {
-      while ( !_heap->empty() && _heap->top()!=dest ) processNextNode();
-      if ( !_heap->empty() ) finalizeNodeData(_heap->top(),_heap->prio());
+    void start(Node t)
+    {
+      while ( !_heap->empty() && _heap->top()!=t ) processNextNode();
+      if ( !_heap->empty() ) {
+        finalizeNodeData(_heap->top(),_heap->prio());
+        _heap->pop();
+      }
     }
 
@@ -773 +776 @@
     }
 
-    ///Runs the algorithm from the given node.
+    ///Runs the algorithm from the given source node.
 
     ///This method runs the %Dijkstra algorithm from node \c s
@@ -797 +800 @@
 
     ///This method runs the %Dijkstra algorithm from node \c s
-    ///in order to compute the shortest path to \c t.
-    ///
-    ///\return The length of the shortest <tt>s</tt>--<tt>t</tt> path,
-    ///if \c t is reachable form \c s, \c 0 otherwise.
+    ///in order to compute the shortest path to node \c t
+    ///(it stops searching when \c t is processed).
+    ///
+    ///\return \c true if \c t is reachable form \c s.
     ///
     ///\note Apart from the return value, <tt>d.run(s,t)</tt> is just a
@@ -809 +812 @@
     ///  d.start(t);
     ///\endcode
-    Value run(Node s,Node t) {
+    bool run(Node s,Node t) {
       init();
       addSource(s);
       start(t);
-      return (*_pred)[t]==INVALID?OperationTraits::zero():(*_dist)[t];
+      return (*_heap_cross_ref)[t] == Heap::POST_HEAP;
     }
 
@@ -909 +912 @@
     ///Returns \c true if \c v is processed, i.e. the shortest
     ///path to \c v has already found.
-    ///\pre Either \ref run() or \ref start()
+    ///\pre Either \ref run() or \ref init()
     ///must be called before using this function.
     bool processed(Node v) const { return (*_heap_cross_ref)[v] ==
@@ -918 +921 @@
     ///Returns the current distance of a node from the root(s).
     ///It may be decreased in the following processes.
-    ///\pre \c v should be reached but not processed.
-    Value currentDist(Node v) const { return (*_heap)[v]; }
+    ///\pre Either \ref run() or \ref init()
+    ///must be called before using this function and
+    ///node \c v must be reached but not necessarily processed.
+    Value currentDist(Node v) const {
+      return processed(v) ? (*_dist)[v] : (*_heap)[v];
+    }
 
     ///@}