graph_to_eps mission accomplished.
- lemon/graph_to_eps.h header created
- lemon/bezier.h: Tools to compute with bezier curves (unclean and undocumented
interface, used internally by graph_to_eps.h)
- demo/graph_to_eps_demo.cc: a simple demo for lemon/graph_to_eps.h
2 * src/lemon/dijkstra.h - Part of LEMON, a generic C++ optimization library
4 * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
5 * (Egervary Combinatorial Optimization Research Group, EGRES).
7 * Permission to use, modify and distribute this software is granted
8 * provided that this copyright notice appears in all copies. For
9 * precise terms see the accompanying LICENSE file.
11 * This software is provided "AS IS" with no warranty of any kind,
12 * express or implied, and with no claim as to its suitability for any
17 #ifndef LEMON_DIJKSTRA_H
18 #define LEMON_DIJKSTRA_H
22 ///\brief Dijkstra algorithm.
24 #include <lemon/bin_heap.h>
25 #include <lemon/invalid.h>
29 /// \addtogroup flowalgs
32 ///%Dijkstra algorithm class.
34 ///This class provides an efficient implementation of %Dijkstra algorithm.
35 ///The edge lengths are passed to the algorithm using a
36 ///\ref concept::ReadMap "ReadMap",
37 ///so it is easy to change it to any kind of length.
39 ///The type of the length is determined by the
40 ///\ref concept::ReadMap::Value "Value" of the length map.
42 ///It is also possible to change the underlying priority heap.
44 ///\param GR The graph type the algorithm runs on.
45 ///\param LM This read-only
48 ///lengths of the edges. It is read once for each edge, so the map
49 ///may involve in relatively time consuming process to compute the edge
50 ///length if it is necessary. The default map type is
51 ///\ref concept::StaticGraph::EdgeMap "Graph::EdgeMap<int>"
52 ///\param Heap The heap type used by the %Dijkstra
53 ///algorithm. The default
54 ///is using \ref BinHeap "binary heap".
56 ///\author Jacint Szabo and Alpar Juttner
57 ///\todo We need a typedef-names should be standardized. (-:
58 ///\todo Type of \c PredMap, \c PredNodeMap and \c DistMap
59 ///should not be fixed. (Problematic to solve).
62 template <typename GR,
66 template <typename GR,
67 typename LM=typename GR::template EdgeMap<int>,
68 template <class,class,class,class> class Heap = BinHeap >
72 ///The type of the underlying graph.
75 typedef typename Graph::Node Node;
77 typedef typename Graph::NodeIt NodeIt;
79 typedef typename Graph::Edge Edge;
81 typedef typename Graph::OutEdgeIt OutEdgeIt;
83 ///The type of the length of the edges.
84 typedef typename LM::Value Value;
85 ///The type of the map that stores the edge lengths.
87 ///\brief The type of the map that stores the last
88 ///edges of the shortest paths.
89 typedef typename Graph::template NodeMap<Edge> PredMap;
90 ///\brief The type of the map that stores the last but one
91 ///nodes of the shortest paths.
92 typedef typename Graph::template NodeMap<Node> PredNodeMap;
93 ///The type of the map that stores the dists of the nodes.
94 typedef typename Graph::template NodeMap<Value> DistMap;
97 /// Pointer to the underlying graph.
99 /// Pointer to the length map
101 ///Pointer to the map of predecessors edges.
102 PredMap *predecessor;
103 ///Indicates if \ref predecessor is locally allocated (\c true) or not.
104 bool local_predecessor;
105 ///Pointer to the map of predecessors nodes.
106 PredNodeMap *pred_node;
107 ///Indicates if \ref pred_node is locally allocated (\c true) or not.
108 bool local_pred_node;
109 ///Pointer to the map of distances.
111 ///Indicates if \ref distance is locally allocated (\c true) or not.
114 ///The source node of the last execution.
117 ///Initializes the maps.
119 ///\todo Error if \c G or are \c NULL. What about \c length?
120 ///\todo Better memory allocation (instead of new).
124 local_predecessor = true;
125 predecessor = new PredMap(*G);
128 local_pred_node = true;
129 pred_node = new PredNodeMap(*G);
132 local_distance = true;
133 distance = new DistMap(*G);
140 ///\param _G the graph the algorithm will run on.
141 ///\param _length the length map used by the algorithm.
142 Dijkstra(const Graph& _G, const LM& _length) :
143 G(&_G), length(&_length),
144 predecessor(NULL), local_predecessor(false),
145 pred_node(NULL), local_pred_node(false),
146 distance(NULL), local_distance(false)
152 if(local_predecessor) delete predecessor;
153 if(local_pred_node) delete pred_node;
154 if(local_distance) delete distance;
157 ///Sets the length map.
159 ///Sets the length map.
160 ///\return <tt> (*this) </tt>
161 Dijkstra &setLengthMap(const LM &m)
167 ///Sets the map storing the predecessor edges.
169 ///Sets the map storing the predecessor edges.
170 ///If you don't use this function before calling \ref run(),
171 ///it will allocate one. The destuctor deallocates this
172 ///automatically allocated map, of course.
173 ///\return <tt> (*this) </tt>
174 Dijkstra &setPredMap(PredMap &m)
176 if(local_predecessor) {
178 local_predecessor=false;
184 ///Sets the map storing the predecessor nodes.
186 ///Sets the map storing the predecessor nodes.
187 ///If you don't use this function before calling \ref run(),
188 ///it will allocate one. The destuctor deallocates this
189 ///automatically allocated map, of course.
190 ///\return <tt> (*this) </tt>
191 Dijkstra &setPredNodeMap(PredNodeMap &m)
193 if(local_pred_node) {
195 local_pred_node=false;
201 ///Sets the map storing the distances calculated by the algorithm.
203 ///Sets the map storing the distances calculated by the algorithm.
204 ///If you don't use this function before calling \ref run(),
205 ///it will allocate one. The destuctor deallocates this
206 ///automatically allocated map, of course.
207 ///\return <tt> (*this) </tt>
208 Dijkstra &setDistMap(DistMap &m)
212 local_distance=false;
218 ///Runs %Dijkstra algorithm from node \c s.
220 ///This method runs the %Dijkstra algorithm from a root node \c s
223 ///shortest path to each node. The algorithm computes
224 ///- The shortest path tree.
225 ///- The distance of each node from the root.
233 for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
234 predecessor->set(u,INVALID);
235 pred_node->set(u,INVALID);
238 typename GR::template NodeMap<int> heap_map(*G,-1);
240 typedef Heap<Node, Value, typename GR::template NodeMap<int>,
244 HeapType heap(heap_map);
248 while ( !heap.empty() ) {
251 Value oldvalue=heap[v];
253 distance->set(v, oldvalue);
256 for(OutEdgeIt e(*G,v); e!=INVALID; ++e) {
258 switch(heap.state(w)) {
259 case HeapType::PRE_HEAP:
260 heap.push(w,oldvalue+(*length)[e]);
261 predecessor->set(w,e);
264 case HeapType::IN_HEAP:
265 if ( oldvalue+(*length)[e] < heap[w] ) {
266 heap.decrease(w, oldvalue+(*length)[e]);
267 predecessor->set(w,e);
271 case HeapType::POST_HEAP:
278 ///The distance of a node from the root.
280 ///Returns the distance of a node from the root.
281 ///\pre \ref run() must be called before using this function.
282 ///\warning If node \c v in unreachable from the root the return value
283 ///of this funcion is undefined.
284 Value dist(Node v) const { return (*distance)[v]; }
286 ///Returns the 'previous edge' of the shortest path tree.
288 ///For a node \c v it returns the 'previous edge' of the shortest path tree,
289 ///i.e. it returns the last edge of a shortest path from the root to \c
290 ///v. It is \ref INVALID
291 ///if \c v is unreachable from the root or if \c v=s. The
292 ///shortest path tree used here is equal to the shortest path tree used in
293 ///\ref predNode(Node v). \pre \ref run() must be called before using
295 ///\todo predEdge could be a better name.
296 Edge pred(Node v) const { return (*predecessor)[v]; }
298 ///Returns the 'previous node' of the shortest path tree.
300 ///For a node \c v it returns the 'previous node' of the shortest path tree,
301 ///i.e. it returns the last but one node from a shortest path from the
302 ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
303 ///\c v=s. The shortest path tree used here is equal to the shortest path
304 ///tree used in \ref pred(Node v). \pre \ref run() must be called before
305 ///using this function.
306 Node predNode(Node v) const { return (*pred_node)[v]; }
308 ///Returns a reference to the NodeMap of distances.
310 ///Returns a reference to the NodeMap of distances. \pre \ref run() must
311 ///be called before using this function.
312 const DistMap &distMap() const { return *distance;}
314 ///Returns a reference to the shortest path tree map.
316 ///Returns a reference to the NodeMap of the edges of the
317 ///shortest path tree.
318 ///\pre \ref run() must be called before using this function.
319 const PredMap &predMap() const { return *predecessor;}
321 ///Returns a reference to the map of nodes of shortest paths.
323 ///Returns a reference to the NodeMap of the last but one nodes of the
324 ///shortest path tree.
325 ///\pre \ref run() must be called before using this function.
326 const PredNodeMap &predNodeMap() const { return *pred_node;}
328 ///Checks if a node is reachable from the root.
330 ///Returns \c true if \c v is reachable from the root.
331 ///\note The root node is reported to be reached!
332 ///\pre \ref run() must be called before using this function.
334 bool reached(Node v) { return v==source || (*predecessor)[v]!=INVALID; }
340 } //END OF NAMESPACE LEMON