Shorter template parameter names to be more readable in Doxygen.
2 #ifndef HUGO_DIJKSTRA_H
3 #define HUGO_DIJKSTRA_H
7 ///\brief Dijkstra algorithm.
9 #include <hugo/bin_heap.h>
10 #include <hugo/invalid.h>
14 /// \addtogroup flowalgs
17 ///%Dijkstra algorithm class.
19 ///This class provides an efficient implementation of %Dijkstra algorithm.
20 ///The edge lengths are passed to the algorithm using a
21 ///\ref ReadMapSkeleton "readable map",
22 ///so it is easy to change it to any kind of length.
24 ///The type of the length is determined by the \c ValueType of the length map.
26 ///It is also possible to change the underlying priority heap.
28 ///\param GR The graph type the algorithm runs on.
29 ///\param LM This read-only
32 ///lengths of the edges. It is read once for each edge, so the map
33 ///may involve in relatively time consuming process to compute the edge
34 ///length if it is necessary. The default map type is
35 ///\ref GraphSkeleton::EdgeMap "Graph::EdgeMap<int>"
36 ///\param Heap The heap type used by the %Dijkstra
37 ///algorithm. The default
38 ///is using \ref BinHeap "binary heap".
40 ///\author Jacint Szabo and Alpar Juttner
41 ///\todo We need a typedef-names should be standardized. (-:
42 ///\todo Type of \c PredMap, \c PredNodeMap and \c DistMap
43 ///should not be fixed. (Problematic to solve).
46 template <typename GR,
50 template <typename GR,
51 typename LM=typename GR::template EdgeMap<int>,
52 template <class,class,class,class> class Heap = BinHeap >
56 ///The type of the underlying graph.
59 typedef typename Graph::Node Node;
61 typedef typename Graph::NodeIt NodeIt;
63 typedef typename Graph::Edge Edge;
65 typedef typename Graph::OutEdgeIt OutEdgeIt;
67 ///The type of the length of the edges.
68 typedef typename LM::ValueType ValueType;
69 ///The type of the map that stores the edge lengths.
71 ///\brief The type of the map that stores the last
72 ///edges of the shortest paths.
73 typedef typename Graph::template NodeMap<Edge> PredMap;
74 ///\brief The type of the map that stores the last but one
75 ///nodes of the shortest paths.
76 typedef typename Graph::template NodeMap<Node> PredNodeMap;
77 ///The type of the map that stores the dists of the nodes.
78 typedef typename Graph::template NodeMap<ValueType> DistMap;
81 /// Pointer to the underlying graph.
83 /// Pointer to the length map
85 ///Pointer to the map of predecessors edges.
87 ///Indicates if \ref predecessor is locally allocated (\c true) or not.
88 bool local_predecessor;
89 ///Pointer to the map of predecessors nodes.
90 PredNodeMap *pred_node;
91 ///Indicates if \ref pred_node is locally allocated (\c true) or not.
93 ///Pointer to the map of distances.
95 ///Indicates if \ref distance is locally allocated (\c true) or not.
98 ///The source node of the last execution.
101 ///Initializes the maps.
103 ///\todo Error if \c G or are \c NULL. What about \c length?
104 ///\todo Better memory allocation (instead of new).
108 local_predecessor = true;
109 predecessor = new PredMap(*G);
112 local_pred_node = true;
113 pred_node = new PredNodeMap(*G);
116 local_distance = true;
117 distance = new DistMap(*G);
124 ///\param _G the graph the algorithm will run on.
125 ///\param _length the length map used by the algorithm.
126 Dijkstra(const Graph& _G, const LM& _length) :
127 G(&_G), length(&_length),
128 predecessor(NULL), local_predecessor(false),
129 pred_node(NULL), local_pred_node(false),
130 distance(NULL), local_distance(false)
136 if(local_predecessor) delete predecessor;
137 if(local_pred_node) delete pred_node;
138 if(local_distance) delete distance;
141 ///Sets the length map.
143 ///Sets the length map.
144 ///\return <tt> (*this) </tt>
145 Dijkstra &setLengthMap(const LM &m)
151 ///Sets the map storing the predecessor edges.
153 ///Sets the map storing the predecessor edges.
154 ///If you don't use this function before calling \ref run(),
155 ///it will allocate one. The destuctor deallocates this
156 ///automatically allocated map, of course.
157 ///\return <tt> (*this) </tt>
158 Dijkstra &setPredMap(PredMap &m)
160 if(local_predecessor) {
162 local_predecessor=false;
168 ///Sets the map storing the predecessor nodes.
170 ///Sets the map storing the predecessor nodes.
171 ///If you don't use this function before calling \ref run(),
172 ///it will allocate one. The destuctor deallocates this
173 ///automatically allocated map, of course.
174 ///\return <tt> (*this) </tt>
175 Dijkstra &setPredNodeMap(PredNodeMap &m)
177 if(local_pred_node) {
179 local_pred_node=false;
185 ///Sets the map storing the distances calculated by the algorithm.
187 ///Sets the map storing the distances calculated by the algorithm.
188 ///If you don't use this function before calling \ref run(),
189 ///it will allocate one. The destuctor deallocates this
190 ///automatically allocated map, of course.
191 ///\return <tt> (*this) </tt>
192 Dijkstra &setDistMap(DistMap &m)
196 local_distance=false;
202 ///Runs %Dijkstra algorithm from node \c s.
204 ///This method runs the %Dijkstra algorithm from a root node \c s
207 ///shortest path to each node. The algorithm computes
208 ///- The shortest path tree.
209 ///- The distance of each node from the root.
217 for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
218 predecessor->set(u,INVALID);
219 pred_node->set(u,INVALID);
222 typename GR::template NodeMap<int> heap_map(*G,-1);
224 typedef Heap<Node, ValueType, typename GR::template NodeMap<int>,
225 std::less<ValueType> >
228 HeapType heap(heap_map);
232 while ( !heap.empty() ) {
235 ValueType oldvalue=heap[v];
237 distance->set(v, oldvalue);
240 for(OutEdgeIt e(*G,v); e!=INVALID; ++e) {
242 switch(heap.state(w)) {
243 case HeapType::PRE_HEAP:
244 heap.push(w,oldvalue+(*length)[e]);
245 predecessor->set(w,e);
248 case HeapType::IN_HEAP:
249 if ( oldvalue+(*length)[e] < heap[w] ) {
250 heap.decrease(w, oldvalue+(*length)[e]);
251 predecessor->set(w,e);
255 case HeapType::POST_HEAP:
262 ///The distance of a node from the root.
264 ///Returns the distance of a node from the root.
265 ///\pre \ref run() must be called before using this function.
266 ///\warning If node \c v in unreachable from the root the return value
267 ///of this funcion is undefined.
268 ValueType dist(Node v) const { return (*distance)[v]; }
270 ///Returns the 'previous edge' of the shortest path tree.
272 ///For a node \c v it returns the 'previous edge' of the shortest path tree,
273 ///i.e. it returns the last edge of a shortest path from the root to \c
274 ///v. It is \ref INVALID
275 ///if \c v is unreachable from the root or if \c v=s. The
276 ///shortest path tree used here is equal to the shortest path tree used in
277 ///\ref predNode(Node v). \pre \ref run() must be called before using
279 ///\todo predEdge could be a better name.
280 Edge pred(Node v) const { return (*predecessor)[v]; }
282 ///Returns the 'previous node' of the shortest path tree.
284 ///For a node \c v it returns the 'previous node' of the shortest path tree,
285 ///i.e. it returns the last but one node from a shortest path from the
286 ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
287 ///\c v=s. The shortest path tree used here is equal to the shortest path
288 ///tree used in \ref pred(Node v). \pre \ref run() must be called before
289 ///using this function.
290 Node predNode(Node v) const { return (*pred_node)[v]; }
292 ///Returns a reference to the NodeMap of distances.
294 ///Returns a reference to the NodeMap of distances. \pre \ref run() must
295 ///be called before using this function.
296 const DistMap &distMap() const { return *distance;}
298 ///Returns a reference to the shortest path tree map.
300 ///Returns a reference to the NodeMap of the edges of the
301 ///shortest path tree.
302 ///\pre \ref run() must be called before using this function.
303 const PredMap &predMap() const { return *predecessor;}
305 ///Returns a reference to the map of nodes of shortest paths.
307 ///Returns a reference to the NodeMap of the last but one nodes of the
308 ///shortest path tree.
309 ///\pre \ref run() must be called before using this function.
310 const PredNodeMap &predNodeMap() const { return *pred_node;}
312 ///Checks if a node is reachable from the root.
314 ///Returns \c true if \c v is reachable from the root.
315 ///\note The root node is reported to be reached!
316 ///\pre \ref run() must be called before using this function.
318 bool reached(Node v) { return v==source || (*predecessor)[v]!=INVALID; }
324 } //END OF NAMESPACE HUGO