diff -r 718479989797 -r 3f1c7a6c33cd lemon/dijkstra.h
--- a/lemon/dijkstra.h	Mon May 07 08:48:40 2007 +0000
+++ b/lemon/dijkstra.h	Mon May 07 08:49:57 2007 +0000
@@ -601,7 +601,7 @@
     /// is empty.
     Node nextNode()
     { 
-      return _heap->empty()?_heap->top():INVALID;
+      return !_heap->empty()?_heap->top():INVALID;
     }
  
     ///\brief Returns \c false if there are nodes
@@ -664,11 +664,16 @@
     ///
     ///\param nm must be a bool (or convertible) node map. The algorithm
     ///will stop when it reaches a node \c v with <tt>nm[v]==true</tt>.
+    ///
+    ///\return The reached node \c v with <tt>nm[v]==true<\tt> or
+    ///\c INVALID if no such node was found.
     template<class NodeBoolMap>
-    void start(const NodeBoolMap &nm)
+    Node start(const NodeBoolMap &nm)
     {
       while ( !_heap->empty() && !nm[_heap->top()] ) processNextNode();
-      if ( !_heap->empty() ) finalizeNodeData(_heap->top(),_heap->prio());
+      if ( _heap->empty() ) return INVALID;
+      finalizeNodeData(_heap->top(),_heap->prio());
+      return _heap->top();
     }
     
     ///Runs %Dijkstra algorithm from node \c s.