Changeset 372:e6a156fc186d in lemon-0.x for src/work/jacint/dijkstra.h

Timestamp:

04/22/04 16:11:28 (20 years ago)

Author:

jacint

Branch:

default

Phase:

public

Convert:

svn:c9d7d8f5-90d6-0310-b91f-818b3a526b0e/lemon/trunk@502

Message:

 

File:

• src/work/jacint/dijkstra.h (modified) (3 diffs)

src/work/jacint/dijkstra.h

@@ -1 +1 @@
 // -*- C++ -*-
+
 /* 
  *template <Graph, T, Heap=FibHeap, LengthMap=Graph::EdgeMap<T> >
@@ -27 +28 @@
 #define HUGO_DIJKSTRA_H
 
+///\file
+///\brief Dijkstra algorithm.
+
 #include <fib_heap.h>
+#include <bin_heap.h>
 #include <invalid.h>
 
 namespace hugo {
   
-  template <typename Graph, typename T, 
-    typename Heap=FibHeap<typename Graph::Node, T, 
-    typename Graph::NodeMap<int> >, 
-    typename LengthMap=typename Graph::EdgeMap<T> >
+  //Alpar: Changed the order of the parameters
+  
+  ///%Dijkstra algorithm class.
+
+  ///This class provides an efficient implementation of %Dijkstra algorithm.
+  ///The edge lengths are passed to the algorithm using a
+  ///\ref ReadMapSkeleton "readable map",
+  ///so it is easy to change it to any kind of length.
+  ///
+  ///The type of the length is determined by the \c ValueType of the length map.
+  ///
+  ///It is also possible to change the underlying priority heap.
+  ///
+  ///\param Graph The graph type the algorithm runs on.
+  ///\param LengthMap This read-only
+  ///EdgeMap
+  ///determines the
+  ///lengths of the edges. It is read once for each edge, so the map
+  ///may involve in relatively time consuming process to compute the edge
+  ///length if it is necessary. The default map type is
+  ///\ref GraphSkeleton::EdgeMap "Graph::EdgeMap<int>"
+  ///\param Heap The heap type used by the %Dijkstra
+  ///algorithm. The default
+  ///is using \ref BinHeap "binary heap".
+  
+#ifdef DOXYGEN
+  template <typename Graph,
+            typename LengthMap,
+            typename Heap>
+#else
+  template <typename Graph,
+            typename LengthMap=typename Graph::EdgeMap<int>,
+            template <class,class,class> class Heap = BinHeap >
+#endif
   class Dijkstra{
+  public:
     typedef typename Graph::Node Node;
     typedef typename Graph::NodeIt NodeIt;
@@ -42 +78 @@
     typedef typename Graph::OutEdgeIt OutEdgeIt;
     
+    typedef typename LengthMap::ValueType ValueType;
+    typedef typename Graph::NodeMap<Edge> PredMap;
+    typedef typename Graph::NodeMap<Node> PredNodeMap;
+    typedef typename Graph::NodeMap<ValueType> DistMap;
+
+  private:
     const Graph& G;
     const LengthMap& length;
-    typename Graph::NodeMap<Edge> predecessor;
-    typename Graph::NodeMap<T> distance;
-    //FIXME:
-    typename Graph::NodeMap<bool> reach;
-    //typename Graph::NodeMap<int> reach;
+    PredMap predecessor;
+    PredNodeMap pred_node;
+    DistMap distance;
     
   public :
     
-    /*
-      The distance of the nodes is 0.
-    */
-    Dijkstra(Graph& _G, LengthMap& _length) : G(_G), 
-      length(_length), predecessor(_G), distance(_G), reach(_G) { }
-    
-
-    void run(Node s) {
-      
-      NodeIt u;
-      for ( G.first(u) ; G.valid(u) ; G.next(u) ) {
-        predecessor.set(u,INVALID);
-        distance.set(u,0);
-        reach.set(u,false);
-      }
-     
-      //FIXME:
-      typename Graph::NodeMap<bool> scanned(G,false);
-      //typename Graph::NodeMap<int> scanned(G,false);
-      typename Graph::NodeMap<int> heap_map(G,-1);
-      
-      Heap heap(heap_map);
-
-      heap.push(s,0); 
-      reach.set(s, true);
-
+    Dijkstra(Graph& _G, LengthMap& _length) :
+      G(_G), length(_length), predecessor(_G), pred_node(_G), distance(_G) { }
+    
+    void run(Node s);
+    
+    ///The distance of a node from the source.
+
+    ///Returns the distance of a node from the source.
+    ///\pre \ref run() must be called before using this function.
+    ///\warning If node \c v in unreachable from the source the return value
+    ///of this funcion is undefined.
+    ValueType dist(Node v) const { return distance[v]; }
+    ///Returns the edges of the shortest path tree.
+
+    ///For a node \c v it returns the last edge of the shortest path
+    ///from the source to \c v or INVALID if \c v is unreachable
+    ///from the source.
+    ///\pre \ref run() must be called before using this function.
+    Edge pred(Node v) const { return predecessor[v]; }
+    ///Returns the nodes of the shortest paths.
+
+    ///For a node \c v it returns the last but one node of the shortest path
+    ///from the source to \c v or INVALID if \c v is unreachable
+    ///from the source.
+    ///\pre \ref run() must be called before using this function.
+    Node predNode(Node v) const { return pred_node[v]; }
+    
+    ///Returns a reference to the NodeMap of distances.
+
+    ///\pre \ref run() must be called before using this function.
+    ///
+    const DistMap &distMap() const { return distance;}
+    ///Returns a reference to the shortest path tree map.
+
+    ///Returns a reference to the NodeMap of the edges of the
+    ///shortest path tree.
+    ///\pre \ref run() must be called before using this function.
+    const PredMap &predMap() const { return predecessor;}
+    ///Returns a reference to the map of nodes of  shortest paths.
+
+    ///Returns a reference to the NodeMap of the last but one nodes of the
+    ///shortest paths.
+    ///\pre \ref run() must be called before using this function.
+    const PredNodeMap &predNodeMap() const { return pred_node;}
+
+    ///Checks if a node is reachable from the source.
+
+    ///Returns \c true if \c v is reachable from the source.
+    ///\warning the source node is reported to be unreached!
+    ///\todo Is this what we want?
+    ///\pre \ref run() must be called before using this function.
+    ///
+    bool reached(Node v) { return G.valid(predecessor[v]); }
+    
+  };
+  
+
+  // **********************************************************************
+  //  IMPLEMENTATIONS
+  // **********************************************************************
+
+  ///Runs %Dijkstra algorithm from node the source.
+
+  ///This method runs the %Dijkstra algorithm from a source node \c s
+  ///in order to
+  ///compute the
+  ///shortest path to each node. The algorithm computes
+  ///- The shortest path tree.
+  ///- The distance of each node from the source.
+  template <typename Graph, typename LengthMap,
+            template<class,class,class> class Heap >
+  void Dijkstra<Graph,LengthMap,Heap>::run(Node s) {
+    
+    NodeIt u;
+    for ( G.first(u) ; G.valid(u) ; G.next(u) ) {
+      predecessor.set(u,INVALID);
+      pred_node.set(u,INVALID);
+      // If a node is unreacheable, then why should be the dist=0?
+      // distance.set(u,0);
+      //      reach.set(u,false);
+    }
+    
+    typename Graph::NodeMap<int> heap_map(G,-1);
+    
+    Heap<Node,ValueType,typename Graph::NodeMap<int> > heap(heap_map);
+    
+    heap.push(s,0); 
+    
       while ( !heap.empty() ) {
         
         Node v=heap.top(); 
-        T oldvalue=heap.get(v);
+        ValueType oldvalue=heap[v];
         heap.pop();
         distance.set(v, oldvalue);
-        scanned.set(v,true);
-
-        OutEdgeIt e;
-        for( G.first(e,v); G.valid(e); G.next(e)) {
+        
+        { //FIXME this bracket is for e to be local
+          OutEdgeIt e;
+        for(G.first(e, v);
+            G.valid(e); G.next(e)) {
           Node w=G.head(e); 
-            
-          if ( !scanned[w] ) {
-            if ( !reach[w] ) {
-              reach.set(w,true);
-              heap.push(w,oldvalue+length[e]); 
+          
+          switch(heap.state(w)) {
+          case heap.PRE_HEAP:
+            heap.push(w,oldvalue+length[e]); 
+            predecessor.set(w,e);
+            pred_node.set(w,v);
+            break;
+          case heap.IN_HEAP:
+            if ( oldvalue+length[e] < heap[w] ) {
+              heap.decrease(w, oldvalue+length[e]); 
               predecessor.set(w,e);
-            } else if ( oldvalue+length[e] < heap.get(w) ) {
-              predecessor.set(w,e);
-              heap.decrease(w, oldvalue+length[e]); 
+              pred_node.set(w,v);
             }
+            break;
+          case heap.POST_HEAP:
+            break;
           }
         }
+      } //FIXME tis bracket
       }
-    }
-    
-    T dist(Node v) {
-      return distance[v];
-    }
-
-    Edge pred(Node v) {
-      return predecessor[v];
-    }
-     
-    bool reached(Node v) {
-      return reach[v];
-    }
-    
-  };
-  
-}
+  }
+  
+} //END OF NAMESPACE HUGO
 
 #endif