1 | /* -*- mode: C++; indent-tabs-mode: nil; -*- |
---|
2 | * |
---|
3 | * This file is a part of LEMON, a generic C++ optimization library. |
---|
4 | * |
---|
5 | * Copyright (C) 2003-2009 |
---|
6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
---|
7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
---|
8 | * |
---|
9 | * Permission to use, modify and distribute this software is granted |
---|
10 | * provided that this copyright notice appears in all copies. For |
---|
11 | * precise terms see the accompanying LICENSE file. |
---|
12 | * |
---|
13 | * This software is provided "AS IS" with no warranty of any kind, |
---|
14 | * express or implied, and with no claim as to its suitability for any |
---|
15 | * purpose. |
---|
16 | * |
---|
17 | */ |
---|
18 | |
---|
19 | #ifndef LEMON_DFS_H |
---|
20 | #define LEMON_DFS_H |
---|
21 | |
---|
22 | ///\ingroup search |
---|
23 | ///\file |
---|
24 | ///\brief DFS algorithm. |
---|
25 | |
---|
26 | #include <lemon/list_graph.h> |
---|
27 | #include <lemon/bits/path_dump.h> |
---|
28 | #include <lemon/core.h> |
---|
29 | #include <lemon/error.h> |
---|
30 | #include <lemon/maps.h> |
---|
31 | #include <lemon/path.h> |
---|
32 | |
---|
33 | namespace lemon { |
---|
34 | |
---|
35 | ///Default traits class of Dfs class. |
---|
36 | |
---|
37 | ///Default traits class of Dfs class. |
---|
38 | ///\tparam GR Digraph type. |
---|
39 | template<class GR> |
---|
40 | struct DfsDefaultTraits |
---|
41 | { |
---|
42 | ///The type of the digraph the algorithm runs on. |
---|
43 | typedef GR Digraph; |
---|
44 | |
---|
45 | ///\brief The type of the map that stores the predecessor |
---|
46 | ///arcs of the %DFS paths. |
---|
47 | /// |
---|
48 | ///The type of the map that stores the predecessor |
---|
49 | ///arcs of the %DFS paths. |
---|
50 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
51 | typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap; |
---|
52 | ///Instantiates a \c PredMap. |
---|
53 | |
---|
54 | ///This function instantiates a \ref PredMap. |
---|
55 | ///\param g is the digraph, to which we would like to define the |
---|
56 | ///\ref PredMap. |
---|
57 | static PredMap *createPredMap(const Digraph &g) |
---|
58 | { |
---|
59 | return new PredMap(g); |
---|
60 | } |
---|
61 | |
---|
62 | ///The type of the map that indicates which nodes are processed. |
---|
63 | |
---|
64 | ///The type of the map that indicates which nodes are processed. |
---|
65 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
66 | typedef NullMap<typename Digraph::Node,bool> ProcessedMap; |
---|
67 | ///Instantiates a \c ProcessedMap. |
---|
68 | |
---|
69 | ///This function instantiates a \ref ProcessedMap. |
---|
70 | ///\param g is the digraph, to which |
---|
71 | ///we would like to define the \ref ProcessedMap. |
---|
72 | #ifdef DOXYGEN |
---|
73 | static ProcessedMap *createProcessedMap(const Digraph &g) |
---|
74 | #else |
---|
75 | static ProcessedMap *createProcessedMap(const Digraph &) |
---|
76 | #endif |
---|
77 | { |
---|
78 | return new ProcessedMap(); |
---|
79 | } |
---|
80 | |
---|
81 | ///The type of the map that indicates which nodes are reached. |
---|
82 | |
---|
83 | ///The type of the map that indicates which nodes are reached. |
---|
84 | ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept. |
---|
85 | typedef typename Digraph::template NodeMap<bool> ReachedMap; |
---|
86 | ///Instantiates a \c ReachedMap. |
---|
87 | |
---|
88 | ///This function instantiates a \ref ReachedMap. |
---|
89 | ///\param g is the digraph, to which |
---|
90 | ///we would like to define the \ref ReachedMap. |
---|
91 | static ReachedMap *createReachedMap(const Digraph &g) |
---|
92 | { |
---|
93 | return new ReachedMap(g); |
---|
94 | } |
---|
95 | |
---|
96 | ///The type of the map that stores the distances of the nodes. |
---|
97 | |
---|
98 | ///The type of the map that stores the distances of the nodes. |
---|
99 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
100 | typedef typename Digraph::template NodeMap<int> DistMap; |
---|
101 | ///Instantiates a \c DistMap. |
---|
102 | |
---|
103 | ///This function instantiates a \ref DistMap. |
---|
104 | ///\param g is the digraph, to which we would like to define the |
---|
105 | ///\ref DistMap. |
---|
106 | static DistMap *createDistMap(const Digraph &g) |
---|
107 | { |
---|
108 | return new DistMap(g); |
---|
109 | } |
---|
110 | }; |
---|
111 | |
---|
112 | ///%DFS algorithm class. |
---|
113 | |
---|
114 | ///\ingroup search |
---|
115 | ///This class provides an efficient implementation of the %DFS algorithm. |
---|
116 | /// |
---|
117 | ///There is also a \ref dfs() "function-type interface" for the DFS |
---|
118 | ///algorithm, which is convenient in the simplier cases and it can be |
---|
119 | ///used easier. |
---|
120 | /// |
---|
121 | ///\tparam GR The type of the digraph the algorithm runs on. |
---|
122 | ///The default type is \ref ListDigraph. |
---|
123 | #ifdef DOXYGEN |
---|
124 | template <typename GR, |
---|
125 | typename TR> |
---|
126 | #else |
---|
127 | template <typename GR=ListDigraph, |
---|
128 | typename TR=DfsDefaultTraits<GR> > |
---|
129 | #endif |
---|
130 | class Dfs { |
---|
131 | public: |
---|
132 | |
---|
133 | ///The type of the digraph the algorithm runs on. |
---|
134 | typedef typename TR::Digraph Digraph; |
---|
135 | |
---|
136 | ///\brief The type of the map that stores the predecessor arcs of the |
---|
137 | ///DFS paths. |
---|
138 | typedef typename TR::PredMap PredMap; |
---|
139 | ///The type of the map that stores the distances of the nodes. |
---|
140 | typedef typename TR::DistMap DistMap; |
---|
141 | ///The type of the map that indicates which nodes are reached. |
---|
142 | typedef typename TR::ReachedMap ReachedMap; |
---|
143 | ///The type of the map that indicates which nodes are processed. |
---|
144 | typedef typename TR::ProcessedMap ProcessedMap; |
---|
145 | ///The type of the paths. |
---|
146 | typedef PredMapPath<Digraph, PredMap> Path; |
---|
147 | |
---|
148 | ///The \ref DfsDefaultTraits "traits class" of the algorithm. |
---|
149 | typedef TR Traits; |
---|
150 | |
---|
151 | private: |
---|
152 | |
---|
153 | typedef typename Digraph::Node Node; |
---|
154 | typedef typename Digraph::NodeIt NodeIt; |
---|
155 | typedef typename Digraph::Arc Arc; |
---|
156 | typedef typename Digraph::OutArcIt OutArcIt; |
---|
157 | |
---|
158 | //Pointer to the underlying digraph. |
---|
159 | const Digraph *G; |
---|
160 | //Pointer to the map of predecessor arcs. |
---|
161 | PredMap *_pred; |
---|
162 | //Indicates if _pred is locally allocated (true) or not. |
---|
163 | bool local_pred; |
---|
164 | //Pointer to the map of distances. |
---|
165 | DistMap *_dist; |
---|
166 | //Indicates if _dist is locally allocated (true) or not. |
---|
167 | bool local_dist; |
---|
168 | //Pointer to the map of reached status of the nodes. |
---|
169 | ReachedMap *_reached; |
---|
170 | //Indicates if _reached is locally allocated (true) or not. |
---|
171 | bool local_reached; |
---|
172 | //Pointer to the map of processed status of the nodes. |
---|
173 | ProcessedMap *_processed; |
---|
174 | //Indicates if _processed is locally allocated (true) or not. |
---|
175 | bool local_processed; |
---|
176 | |
---|
177 | std::vector<typename Digraph::OutArcIt> _stack; |
---|
178 | int _stack_head; |
---|
179 | |
---|
180 | //Creates the maps if necessary. |
---|
181 | void create_maps() |
---|
182 | { |
---|
183 | if(!_pred) { |
---|
184 | local_pred = true; |
---|
185 | _pred = Traits::createPredMap(*G); |
---|
186 | } |
---|
187 | if(!_dist) { |
---|
188 | local_dist = true; |
---|
189 | _dist = Traits::createDistMap(*G); |
---|
190 | } |
---|
191 | if(!_reached) { |
---|
192 | local_reached = true; |
---|
193 | _reached = Traits::createReachedMap(*G); |
---|
194 | } |
---|
195 | if(!_processed) { |
---|
196 | local_processed = true; |
---|
197 | _processed = Traits::createProcessedMap(*G); |
---|
198 | } |
---|
199 | } |
---|
200 | |
---|
201 | protected: |
---|
202 | |
---|
203 | Dfs() {} |
---|
204 | |
---|
205 | public: |
---|
206 | |
---|
207 | typedef Dfs Create; |
---|
208 | |
---|
209 | ///\name Named template parameters |
---|
210 | |
---|
211 | ///@{ |
---|
212 | |
---|
213 | template <class T> |
---|
214 | struct SetPredMapTraits : public Traits { |
---|
215 | typedef T PredMap; |
---|
216 | static PredMap *createPredMap(const Digraph &) |
---|
217 | { |
---|
218 | LEMON_ASSERT(false, "PredMap is not initialized"); |
---|
219 | return 0; // ignore warnings |
---|
220 | } |
---|
221 | }; |
---|
222 | ///\brief \ref named-templ-param "Named parameter" for setting |
---|
223 | ///\c PredMap type. |
---|
224 | /// |
---|
225 | ///\ref named-templ-param "Named parameter" for setting |
---|
226 | ///\c PredMap type. |
---|
227 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
228 | template <class T> |
---|
229 | struct SetPredMap : public Dfs<Digraph, SetPredMapTraits<T> > { |
---|
230 | typedef Dfs<Digraph, SetPredMapTraits<T> > Create; |
---|
231 | }; |
---|
232 | |
---|
233 | template <class T> |
---|
234 | struct SetDistMapTraits : public Traits { |
---|
235 | typedef T DistMap; |
---|
236 | static DistMap *createDistMap(const Digraph &) |
---|
237 | { |
---|
238 | LEMON_ASSERT(false, "DistMap is not initialized"); |
---|
239 | return 0; // ignore warnings |
---|
240 | } |
---|
241 | }; |
---|
242 | ///\brief \ref named-templ-param "Named parameter" for setting |
---|
243 | ///\c DistMap type. |
---|
244 | /// |
---|
245 | ///\ref named-templ-param "Named parameter" for setting |
---|
246 | ///\c DistMap type. |
---|
247 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
248 | template <class T> |
---|
249 | struct SetDistMap : public Dfs< Digraph, SetDistMapTraits<T> > { |
---|
250 | typedef Dfs<Digraph, SetDistMapTraits<T> > Create; |
---|
251 | }; |
---|
252 | |
---|
253 | template <class T> |
---|
254 | struct SetReachedMapTraits : public Traits { |
---|
255 | typedef T ReachedMap; |
---|
256 | static ReachedMap *createReachedMap(const Digraph &) |
---|
257 | { |
---|
258 | LEMON_ASSERT(false, "ReachedMap is not initialized"); |
---|
259 | return 0; // ignore warnings |
---|
260 | } |
---|
261 | }; |
---|
262 | ///\brief \ref named-templ-param "Named parameter" for setting |
---|
263 | ///\c ReachedMap type. |
---|
264 | /// |
---|
265 | ///\ref named-templ-param "Named parameter" for setting |
---|
266 | ///\c ReachedMap type. |
---|
267 | ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept. |
---|
268 | template <class T> |
---|
269 | struct SetReachedMap : public Dfs< Digraph, SetReachedMapTraits<T> > { |
---|
270 | typedef Dfs< Digraph, SetReachedMapTraits<T> > Create; |
---|
271 | }; |
---|
272 | |
---|
273 | template <class T> |
---|
274 | struct SetProcessedMapTraits : public Traits { |
---|
275 | typedef T ProcessedMap; |
---|
276 | static ProcessedMap *createProcessedMap(const Digraph &) |
---|
277 | { |
---|
278 | LEMON_ASSERT(false, "ProcessedMap is not initialized"); |
---|
279 | return 0; // ignore warnings |
---|
280 | } |
---|
281 | }; |
---|
282 | ///\brief \ref named-templ-param "Named parameter" for setting |
---|
283 | ///\c ProcessedMap type. |
---|
284 | /// |
---|
285 | ///\ref named-templ-param "Named parameter" for setting |
---|
286 | ///\c ProcessedMap type. |
---|
287 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
288 | template <class T> |
---|
289 | struct SetProcessedMap : public Dfs< Digraph, SetProcessedMapTraits<T> > { |
---|
290 | typedef Dfs< Digraph, SetProcessedMapTraits<T> > Create; |
---|
291 | }; |
---|
292 | |
---|
293 | struct SetStandardProcessedMapTraits : public Traits { |
---|
294 | typedef typename Digraph::template NodeMap<bool> ProcessedMap; |
---|
295 | static ProcessedMap *createProcessedMap(const Digraph &g) |
---|
296 | { |
---|
297 | return new ProcessedMap(g); |
---|
298 | } |
---|
299 | }; |
---|
300 | ///\brief \ref named-templ-param "Named parameter" for setting |
---|
301 | ///\c ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>. |
---|
302 | /// |
---|
303 | ///\ref named-templ-param "Named parameter" for setting |
---|
304 | ///\c ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>. |
---|
305 | ///If you don't set it explicitly, it will be automatically allocated. |
---|
306 | struct SetStandardProcessedMap : |
---|
307 | public Dfs< Digraph, SetStandardProcessedMapTraits > { |
---|
308 | typedef Dfs< Digraph, SetStandardProcessedMapTraits > Create; |
---|
309 | }; |
---|
310 | |
---|
311 | ///@} |
---|
312 | |
---|
313 | public: |
---|
314 | |
---|
315 | ///Constructor. |
---|
316 | |
---|
317 | ///Constructor. |
---|
318 | ///\param g The digraph the algorithm runs on. |
---|
319 | Dfs(const Digraph &g) : |
---|
320 | G(&g), |
---|
321 | _pred(NULL), local_pred(false), |
---|
322 | _dist(NULL), local_dist(false), |
---|
323 | _reached(NULL), local_reached(false), |
---|
324 | _processed(NULL), local_processed(false) |
---|
325 | { } |
---|
326 | |
---|
327 | ///Destructor. |
---|
328 | ~Dfs() |
---|
329 | { |
---|
330 | if(local_pred) delete _pred; |
---|
331 | if(local_dist) delete _dist; |
---|
332 | if(local_reached) delete _reached; |
---|
333 | if(local_processed) delete _processed; |
---|
334 | } |
---|
335 | |
---|
336 | ///Sets the map that stores the predecessor arcs. |
---|
337 | |
---|
338 | ///Sets the map that stores the predecessor arcs. |
---|
339 | ///If you don't use this function before calling \ref run(Node) "run()" |
---|
340 | ///or \ref init(), an instance will be allocated automatically. |
---|
341 | ///The destructor deallocates this automatically allocated map, |
---|
342 | ///of course. |
---|
343 | ///\return <tt> (*this) </tt> |
---|
344 | Dfs &predMap(PredMap &m) |
---|
345 | { |
---|
346 | if(local_pred) { |
---|
347 | delete _pred; |
---|
348 | local_pred=false; |
---|
349 | } |
---|
350 | _pred = &m; |
---|
351 | return *this; |
---|
352 | } |
---|
353 | |
---|
354 | ///Sets the map that indicates which nodes are reached. |
---|
355 | |
---|
356 | ///Sets the map that indicates which nodes are reached. |
---|
357 | ///If you don't use this function before calling \ref run(Node) "run()" |
---|
358 | ///or \ref init(), an instance will be allocated automatically. |
---|
359 | ///The destructor deallocates this automatically allocated map, |
---|
360 | ///of course. |
---|
361 | ///\return <tt> (*this) </tt> |
---|
362 | Dfs &reachedMap(ReachedMap &m) |
---|
363 | { |
---|
364 | if(local_reached) { |
---|
365 | delete _reached; |
---|
366 | local_reached=false; |
---|
367 | } |
---|
368 | _reached = &m; |
---|
369 | return *this; |
---|
370 | } |
---|
371 | |
---|
372 | ///Sets the map that indicates which nodes are processed. |
---|
373 | |
---|
374 | ///Sets the map that indicates which nodes are processed. |
---|
375 | ///If you don't use this function before calling \ref run(Node) "run()" |
---|
376 | ///or \ref init(), an instance will be allocated automatically. |
---|
377 | ///The destructor deallocates this automatically allocated map, |
---|
378 | ///of course. |
---|
379 | ///\return <tt> (*this) </tt> |
---|
380 | Dfs &processedMap(ProcessedMap &m) |
---|
381 | { |
---|
382 | if(local_processed) { |
---|
383 | delete _processed; |
---|
384 | local_processed=false; |
---|
385 | } |
---|
386 | _processed = &m; |
---|
387 | return *this; |
---|
388 | } |
---|
389 | |
---|
390 | ///Sets the map that stores the distances of the nodes. |
---|
391 | |
---|
392 | ///Sets the map that stores the distances of the nodes calculated by |
---|
393 | ///the algorithm. |
---|
394 | ///If you don't use this function before calling \ref run(Node) "run()" |
---|
395 | ///or \ref init(), an instance will be allocated automatically. |
---|
396 | ///The destructor deallocates this automatically allocated map, |
---|
397 | ///of course. |
---|
398 | ///\return <tt> (*this) </tt> |
---|
399 | Dfs &distMap(DistMap &m) |
---|
400 | { |
---|
401 | if(local_dist) { |
---|
402 | delete _dist; |
---|
403 | local_dist=false; |
---|
404 | } |
---|
405 | _dist = &m; |
---|
406 | return *this; |
---|
407 | } |
---|
408 | |
---|
409 | public: |
---|
410 | |
---|
411 | ///\name Execution Control |
---|
412 | ///The simplest way to execute the DFS algorithm is to use one of the |
---|
413 | ///member functions called \ref run(Node) "run()".\n |
---|
414 | ///If you need more control on the execution, first you have to call |
---|
415 | ///\ref init(), then you can add a source node with \ref addSource() |
---|
416 | ///and perform the actual computation with \ref start(). |
---|
417 | ///This procedure can be repeated if there are nodes that have not |
---|
418 | ///been reached. |
---|
419 | |
---|
420 | ///@{ |
---|
421 | |
---|
422 | ///\brief Initializes the internal data structures. |
---|
423 | /// |
---|
424 | ///Initializes the internal data structures. |
---|
425 | void init() |
---|
426 | { |
---|
427 | create_maps(); |
---|
428 | _stack.resize(countNodes(*G)); |
---|
429 | _stack_head=-1; |
---|
430 | for ( NodeIt u(*G) ; u!=INVALID ; ++u ) { |
---|
431 | _pred->set(u,INVALID); |
---|
432 | _reached->set(u,false); |
---|
433 | _processed->set(u,false); |
---|
434 | } |
---|
435 | } |
---|
436 | |
---|
437 | ///Adds a new source node. |
---|
438 | |
---|
439 | ///Adds a new source node to the set of nodes to be processed. |
---|
440 | /// |
---|
441 | ///\pre The stack must be empty. Otherwise the algorithm gives |
---|
442 | ///wrong results. (One of the outgoing arcs of all the source nodes |
---|
443 | ///except for the last one will not be visited and distances will |
---|
444 | ///also be wrong.) |
---|
445 | void addSource(Node s) |
---|
446 | { |
---|
447 | LEMON_DEBUG(emptyQueue(), "The stack is not empty."); |
---|
448 | if(!(*_reached)[s]) |
---|
449 | { |
---|
450 | _reached->set(s,true); |
---|
451 | _pred->set(s,INVALID); |
---|
452 | OutArcIt e(*G,s); |
---|
453 | if(e!=INVALID) { |
---|
454 | _stack[++_stack_head]=e; |
---|
455 | _dist->set(s,_stack_head); |
---|
456 | } |
---|
457 | else { |
---|
458 | _processed->set(s,true); |
---|
459 | _dist->set(s,0); |
---|
460 | } |
---|
461 | } |
---|
462 | } |
---|
463 | |
---|
464 | ///Processes the next arc. |
---|
465 | |
---|
466 | ///Processes the next arc. |
---|
467 | /// |
---|
468 | ///\return The processed arc. |
---|
469 | /// |
---|
470 | ///\pre The stack must not be empty. |
---|
471 | Arc processNextArc() |
---|
472 | { |
---|
473 | Node m; |
---|
474 | Arc e=_stack[_stack_head]; |
---|
475 | if(!(*_reached)[m=G->target(e)]) { |
---|
476 | _pred->set(m,e); |
---|
477 | _reached->set(m,true); |
---|
478 | ++_stack_head; |
---|
479 | _stack[_stack_head] = OutArcIt(*G, m); |
---|
480 | _dist->set(m,_stack_head); |
---|
481 | } |
---|
482 | else { |
---|
483 | m=G->source(e); |
---|
484 | ++_stack[_stack_head]; |
---|
485 | } |
---|
486 | while(_stack_head>=0 && _stack[_stack_head]==INVALID) { |
---|
487 | _processed->set(m,true); |
---|
488 | --_stack_head; |
---|
489 | if(_stack_head>=0) { |
---|
490 | m=G->source(_stack[_stack_head]); |
---|
491 | ++_stack[_stack_head]; |
---|
492 | } |
---|
493 | } |
---|
494 | return e; |
---|
495 | } |
---|
496 | |
---|
497 | ///Next arc to be processed. |
---|
498 | |
---|
499 | ///Next arc to be processed. |
---|
500 | /// |
---|
501 | ///\return The next arc to be processed or \c INVALID if the stack |
---|
502 | ///is empty. |
---|
503 | OutArcIt nextArc() const |
---|
504 | { |
---|
505 | return _stack_head>=0?_stack[_stack_head]:INVALID; |
---|
506 | } |
---|
507 | |
---|
508 | ///Returns \c false if there are nodes to be processed. |
---|
509 | |
---|
510 | ///Returns \c false if there are nodes to be processed |
---|
511 | ///in the queue (stack). |
---|
512 | bool emptyQueue() const { return _stack_head<0; } |
---|
513 | |
---|
514 | ///Returns the number of the nodes to be processed. |
---|
515 | |
---|
516 | ///Returns the number of the nodes to be processed |
---|
517 | ///in the queue (stack). |
---|
518 | int queueSize() const { return _stack_head+1; } |
---|
519 | |
---|
520 | ///Executes the algorithm. |
---|
521 | |
---|
522 | ///Executes the algorithm. |
---|
523 | /// |
---|
524 | ///This method runs the %DFS algorithm from the root node |
---|
525 | ///in order to compute the DFS path to each node. |
---|
526 | /// |
---|
527 | /// The algorithm computes |
---|
528 | ///- the %DFS tree, |
---|
529 | ///- the distance of each node from the root in the %DFS tree. |
---|
530 | /// |
---|
531 | ///\pre init() must be called and a root node should be |
---|
532 | ///added with addSource() before using this function. |
---|
533 | /// |
---|
534 | ///\note <tt>d.start()</tt> is just a shortcut of the following code. |
---|
535 | ///\code |
---|
536 | /// while ( !d.emptyQueue() ) { |
---|
537 | /// d.processNextArc(); |
---|
538 | /// } |
---|
539 | ///\endcode |
---|
540 | void start() |
---|
541 | { |
---|
542 | while ( !emptyQueue() ) processNextArc(); |
---|
543 | } |
---|
544 | |
---|
545 | ///Executes the algorithm until the given target node is reached. |
---|
546 | |
---|
547 | ///Executes the algorithm until the given target node is reached. |
---|
548 | /// |
---|
549 | ///This method runs the %DFS algorithm from the root node |
---|
550 | ///in order to compute the DFS path to \c t. |
---|
551 | /// |
---|
552 | ///The algorithm computes |
---|
553 | ///- the %DFS path to \c t, |
---|
554 | ///- the distance of \c t from the root in the %DFS tree. |
---|
555 | /// |
---|
556 | ///\pre init() must be called and a root node should be |
---|
557 | ///added with addSource() before using this function. |
---|
558 | void start(Node t) |
---|
559 | { |
---|
560 | while ( !emptyQueue() && G->target(_stack[_stack_head])!=t ) |
---|
561 | processNextArc(); |
---|
562 | } |
---|
563 | |
---|
564 | ///Executes the algorithm until a condition is met. |
---|
565 | |
---|
566 | ///Executes the algorithm until a condition is met. |
---|
567 | /// |
---|
568 | ///This method runs the %DFS algorithm from the root node |
---|
569 | ///until an arc \c a with <tt>am[a]</tt> true is found. |
---|
570 | /// |
---|
571 | ///\param am A \c bool (or convertible) arc map. The algorithm |
---|
572 | ///will stop when it reaches an arc \c a with <tt>am[a]</tt> true. |
---|
573 | /// |
---|
574 | ///\return The reached arc \c a with <tt>am[a]</tt> true or |
---|
575 | ///\c INVALID if no such arc was found. |
---|
576 | /// |
---|
577 | ///\pre init() must be called and a root node should be |
---|
578 | ///added with addSource() before using this function. |
---|
579 | /// |
---|
580 | ///\warning Contrary to \ref Bfs and \ref Dijkstra, \c am is an arc map, |
---|
581 | ///not a node map. |
---|
582 | template<class ArcBoolMap> |
---|
583 | Arc start(const ArcBoolMap &am) |
---|
584 | { |
---|
585 | while ( !emptyQueue() && !am[_stack[_stack_head]] ) |
---|
586 | processNextArc(); |
---|
587 | return emptyQueue() ? INVALID : _stack[_stack_head]; |
---|
588 | } |
---|
589 | |
---|
590 | ///Runs the algorithm from the given source node. |
---|
591 | |
---|
592 | ///This method runs the %DFS algorithm from node \c s |
---|
593 | ///in order to compute the DFS path to each node. |
---|
594 | /// |
---|
595 | ///The algorithm computes |
---|
596 | ///- the %DFS tree, |
---|
597 | ///- the distance of each node from the root in the %DFS tree. |
---|
598 | /// |
---|
599 | ///\note <tt>d.run(s)</tt> is just a shortcut of the following code. |
---|
600 | ///\code |
---|
601 | /// d.init(); |
---|
602 | /// d.addSource(s); |
---|
603 | /// d.start(); |
---|
604 | ///\endcode |
---|
605 | void run(Node s) { |
---|
606 | init(); |
---|
607 | addSource(s); |
---|
608 | start(); |
---|
609 | } |
---|
610 | |
---|
611 | ///Finds the %DFS path between \c s and \c t. |
---|
612 | |
---|
613 | ///This method runs the %DFS algorithm from node \c s |
---|
614 | ///in order to compute the DFS path to node \c t |
---|
615 | ///(it stops searching when \c t is processed) |
---|
616 | /// |
---|
617 | ///\return \c true if \c t is reachable form \c s. |
---|
618 | /// |
---|
619 | ///\note Apart from the return value, <tt>d.run(s,t)</tt> is |
---|
620 | ///just a shortcut of the following code. |
---|
621 | ///\code |
---|
622 | /// d.init(); |
---|
623 | /// d.addSource(s); |
---|
624 | /// d.start(t); |
---|
625 | ///\endcode |
---|
626 | bool run(Node s,Node t) { |
---|
627 | init(); |
---|
628 | addSource(s); |
---|
629 | start(t); |
---|
630 | return reached(t); |
---|
631 | } |
---|
632 | |
---|
633 | ///Runs the algorithm to visit all nodes in the digraph. |
---|
634 | |
---|
635 | ///This method runs the %DFS algorithm in order to compute the |
---|
636 | ///%DFS path to each node. |
---|
637 | /// |
---|
638 | ///The algorithm computes |
---|
639 | ///- the %DFS tree (forest), |
---|
640 | ///- the distance of each node from the root(s) in the %DFS tree. |
---|
641 | /// |
---|
642 | ///\note <tt>d.run()</tt> is just a shortcut of the following code. |
---|
643 | ///\code |
---|
644 | /// d.init(); |
---|
645 | /// for (NodeIt n(digraph); n != INVALID; ++n) { |
---|
646 | /// if (!d.reached(n)) { |
---|
647 | /// d.addSource(n); |
---|
648 | /// d.start(); |
---|
649 | /// } |
---|
650 | /// } |
---|
651 | ///\endcode |
---|
652 | void run() { |
---|
653 | init(); |
---|
654 | for (NodeIt it(*G); it != INVALID; ++it) { |
---|
655 | if (!reached(it)) { |
---|
656 | addSource(it); |
---|
657 | start(); |
---|
658 | } |
---|
659 | } |
---|
660 | } |
---|
661 | |
---|
662 | ///@} |
---|
663 | |
---|
664 | ///\name Query Functions |
---|
665 | ///The results of the DFS algorithm can be obtained using these |
---|
666 | ///functions.\n |
---|
667 | ///Either \ref run(Node) "run()" or \ref start() should be called |
---|
668 | ///before using them. |
---|
669 | |
---|
670 | ///@{ |
---|
671 | |
---|
672 | ///The DFS path to a node. |
---|
673 | |
---|
674 | ///Returns the DFS path to a node. |
---|
675 | /// |
---|
676 | ///\warning \c t should be reached from the root(s). |
---|
677 | /// |
---|
678 | ///\pre Either \ref run(Node) "run()" or \ref init() |
---|
679 | ///must be called before using this function. |
---|
680 | Path path(Node t) const { return Path(*G, *_pred, t); } |
---|
681 | |
---|
682 | ///The distance of a node from the root(s). |
---|
683 | |
---|
684 | ///Returns the distance of a node from the root(s). |
---|
685 | /// |
---|
686 | ///\warning If node \c v is not reached from the root(s), then |
---|
687 | ///the return value of this function is undefined. |
---|
688 | /// |
---|
689 | ///\pre Either \ref run(Node) "run()" or \ref init() |
---|
690 | ///must be called before using this function. |
---|
691 | int dist(Node v) const { return (*_dist)[v]; } |
---|
692 | |
---|
693 | ///Returns the 'previous arc' of the %DFS tree for a node. |
---|
694 | |
---|
695 | ///This function returns the 'previous arc' of the %DFS tree for the |
---|
696 | ///node \c v, i.e. it returns the last arc of a %DFS path from a |
---|
697 | ///root to \c v. It is \c INVALID if \c v is not reached from the |
---|
698 | ///root(s) or if \c v is a root. |
---|
699 | /// |
---|
700 | ///The %DFS tree used here is equal to the %DFS tree used in |
---|
701 | ///\ref predNode(). |
---|
702 | /// |
---|
703 | ///\pre Either \ref run(Node) "run()" or \ref init() |
---|
704 | ///must be called before using this function. |
---|
705 | Arc predArc(Node v) const { return (*_pred)[v];} |
---|
706 | |
---|
707 | ///Returns the 'previous node' of the %DFS tree. |
---|
708 | |
---|
709 | ///This function returns the 'previous node' of the %DFS |
---|
710 | ///tree for the node \c v, i.e. it returns the last but one node |
---|
711 | ///from a %DFS path from a root to \c v. It is \c INVALID |
---|
712 | ///if \c v is not reached from the root(s) or if \c v is a root. |
---|
713 | /// |
---|
714 | ///The %DFS tree used here is equal to the %DFS tree used in |
---|
715 | ///\ref predArc(). |
---|
716 | /// |
---|
717 | ///\pre Either \ref run(Node) "run()" or \ref init() |
---|
718 | ///must be called before using this function. |
---|
719 | Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID: |
---|
720 | G->source((*_pred)[v]); } |
---|
721 | |
---|
722 | ///\brief Returns a const reference to the node map that stores the |
---|
723 | ///distances of the nodes. |
---|
724 | /// |
---|
725 | ///Returns a const reference to the node map that stores the |
---|
726 | ///distances of the nodes calculated by the algorithm. |
---|
727 | /// |
---|
728 | ///\pre Either \ref run(Node) "run()" or \ref init() |
---|
729 | ///must be called before using this function. |
---|
730 | const DistMap &distMap() const { return *_dist;} |
---|
731 | |
---|
732 | ///\brief Returns a const reference to the node map that stores the |
---|
733 | ///predecessor arcs. |
---|
734 | /// |
---|
735 | ///Returns a const reference to the node map that stores the predecessor |
---|
736 | ///arcs, which form the DFS tree. |
---|
737 | /// |
---|
738 | ///\pre Either \ref run(Node) "run()" or \ref init() |
---|
739 | ///must be called before using this function. |
---|
740 | const PredMap &predMap() const { return *_pred;} |
---|
741 | |
---|
742 | ///Checks if a node is reached from the root(s). |
---|
743 | |
---|
744 | ///Returns \c true if \c v is reached from the root(s). |
---|
745 | /// |
---|
746 | ///\pre Either \ref run(Node) "run()" or \ref init() |
---|
747 | ///must be called before using this function. |
---|
748 | bool reached(Node v) const { return (*_reached)[v]; } |
---|
749 | |
---|
750 | ///@} |
---|
751 | }; |
---|
752 | |
---|
753 | ///Default traits class of dfs() function. |
---|
754 | |
---|
755 | ///Default traits class of dfs() function. |
---|
756 | ///\tparam GR Digraph type. |
---|
757 | template<class GR> |
---|
758 | struct DfsWizardDefaultTraits |
---|
759 | { |
---|
760 | ///The type of the digraph the algorithm runs on. |
---|
761 | typedef GR Digraph; |
---|
762 | |
---|
763 | ///\brief The type of the map that stores the predecessor |
---|
764 | ///arcs of the %DFS paths. |
---|
765 | /// |
---|
766 | ///The type of the map that stores the predecessor |
---|
767 | ///arcs of the %DFS paths. |
---|
768 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
769 | typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap; |
---|
770 | ///Instantiates a PredMap. |
---|
771 | |
---|
772 | ///This function instantiates a PredMap. |
---|
773 | ///\param g is the digraph, to which we would like to define the |
---|
774 | ///PredMap. |
---|
775 | static PredMap *createPredMap(const Digraph &g) |
---|
776 | { |
---|
777 | return new PredMap(g); |
---|
778 | } |
---|
779 | |
---|
780 | ///The type of the map that indicates which nodes are processed. |
---|
781 | |
---|
782 | ///The type of the map that indicates which nodes are processed. |
---|
783 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
784 | ///By default it is a NullMap. |
---|
785 | typedef NullMap<typename Digraph::Node,bool> ProcessedMap; |
---|
786 | ///Instantiates a ProcessedMap. |
---|
787 | |
---|
788 | ///This function instantiates a ProcessedMap. |
---|
789 | ///\param g is the digraph, to which |
---|
790 | ///we would like to define the ProcessedMap. |
---|
791 | #ifdef DOXYGEN |
---|
792 | static ProcessedMap *createProcessedMap(const Digraph &g) |
---|
793 | #else |
---|
794 | static ProcessedMap *createProcessedMap(const Digraph &) |
---|
795 | #endif |
---|
796 | { |
---|
797 | return new ProcessedMap(); |
---|
798 | } |
---|
799 | |
---|
800 | ///The type of the map that indicates which nodes are reached. |
---|
801 | |
---|
802 | ///The type of the map that indicates which nodes are reached. |
---|
803 | ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept. |
---|
804 | typedef typename Digraph::template NodeMap<bool> ReachedMap; |
---|
805 | ///Instantiates a ReachedMap. |
---|
806 | |
---|
807 | ///This function instantiates a ReachedMap. |
---|
808 | ///\param g is the digraph, to which |
---|
809 | ///we would like to define the ReachedMap. |
---|
810 | static ReachedMap *createReachedMap(const Digraph &g) |
---|
811 | { |
---|
812 | return new ReachedMap(g); |
---|
813 | } |
---|
814 | |
---|
815 | ///The type of the map that stores the distances of the nodes. |
---|
816 | |
---|
817 | ///The type of the map that stores the distances of the nodes. |
---|
818 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
819 | typedef typename Digraph::template NodeMap<int> DistMap; |
---|
820 | ///Instantiates a DistMap. |
---|
821 | |
---|
822 | ///This function instantiates a DistMap. |
---|
823 | ///\param g is the digraph, to which we would like to define |
---|
824 | ///the DistMap |
---|
825 | static DistMap *createDistMap(const Digraph &g) |
---|
826 | { |
---|
827 | return new DistMap(g); |
---|
828 | } |
---|
829 | |
---|
830 | ///The type of the DFS paths. |
---|
831 | |
---|
832 | ///The type of the DFS paths. |
---|
833 | ///It must meet the \ref concepts::Path "Path" concept. |
---|
834 | typedef lemon::Path<Digraph> Path; |
---|
835 | }; |
---|
836 | |
---|
837 | /// Default traits class used by DfsWizard |
---|
838 | |
---|
839 | /// To make it easier to use Dfs algorithm |
---|
840 | /// we have created a wizard class. |
---|
841 | /// This \ref DfsWizard class needs default traits, |
---|
842 | /// as well as the \ref Dfs class. |
---|
843 | /// The \ref DfsWizardBase is a class to be the default traits of the |
---|
844 | /// \ref DfsWizard class. |
---|
845 | template<class GR> |
---|
846 | class DfsWizardBase : public DfsWizardDefaultTraits<GR> |
---|
847 | { |
---|
848 | |
---|
849 | typedef DfsWizardDefaultTraits<GR> Base; |
---|
850 | protected: |
---|
851 | //The type of the nodes in the digraph. |
---|
852 | typedef typename Base::Digraph::Node Node; |
---|
853 | |
---|
854 | //Pointer to the digraph the algorithm runs on. |
---|
855 | void *_g; |
---|
856 | //Pointer to the map of reached nodes. |
---|
857 | void *_reached; |
---|
858 | //Pointer to the map of processed nodes. |
---|
859 | void *_processed; |
---|
860 | //Pointer to the map of predecessors arcs. |
---|
861 | void *_pred; |
---|
862 | //Pointer to the map of distances. |
---|
863 | void *_dist; |
---|
864 | //Pointer to the DFS path to the target node. |
---|
865 | void *_path; |
---|
866 | //Pointer to the distance of the target node. |
---|
867 | int *_di; |
---|
868 | |
---|
869 | public: |
---|
870 | /// Constructor. |
---|
871 | |
---|
872 | /// This constructor does not require parameters, therefore it initiates |
---|
873 | /// all of the attributes to \c 0. |
---|
874 | DfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0), |
---|
875 | _dist(0), _path(0), _di(0) {} |
---|
876 | |
---|
877 | /// Constructor. |
---|
878 | |
---|
879 | /// This constructor requires one parameter, |
---|
880 | /// others are initiated to \c 0. |
---|
881 | /// \param g The digraph the algorithm runs on. |
---|
882 | DfsWizardBase(const GR &g) : |
---|
883 | _g(reinterpret_cast<void*>(const_cast<GR*>(&g))), |
---|
884 | _reached(0), _processed(0), _pred(0), _dist(0), _path(0), _di(0) {} |
---|
885 | |
---|
886 | }; |
---|
887 | |
---|
888 | /// Auxiliary class for the function-type interface of DFS algorithm. |
---|
889 | |
---|
890 | /// This auxiliary class is created to implement the |
---|
891 | /// \ref dfs() "function-type interface" of \ref Dfs algorithm. |
---|
892 | /// It does not have own \ref run(Node) "run()" method, it uses the |
---|
893 | /// functions and features of the plain \ref Dfs. |
---|
894 | /// |
---|
895 | /// This class should only be used through the \ref dfs() function, |
---|
896 | /// which makes it easier to use the algorithm. |
---|
897 | template<class TR> |
---|
898 | class DfsWizard : public TR |
---|
899 | { |
---|
900 | typedef TR Base; |
---|
901 | |
---|
902 | ///The type of the digraph the algorithm runs on. |
---|
903 | typedef typename TR::Digraph Digraph; |
---|
904 | |
---|
905 | typedef typename Digraph::Node Node; |
---|
906 | typedef typename Digraph::NodeIt NodeIt; |
---|
907 | typedef typename Digraph::Arc Arc; |
---|
908 | typedef typename Digraph::OutArcIt OutArcIt; |
---|
909 | |
---|
910 | ///\brief The type of the map that stores the predecessor |
---|
911 | ///arcs of the DFS paths. |
---|
912 | typedef typename TR::PredMap PredMap; |
---|
913 | ///\brief The type of the map that stores the distances of the nodes. |
---|
914 | typedef typename TR::DistMap DistMap; |
---|
915 | ///\brief The type of the map that indicates which nodes are reached. |
---|
916 | typedef typename TR::ReachedMap ReachedMap; |
---|
917 | ///\brief The type of the map that indicates which nodes are processed. |
---|
918 | typedef typename TR::ProcessedMap ProcessedMap; |
---|
919 | ///The type of the DFS paths |
---|
920 | typedef typename TR::Path Path; |
---|
921 | |
---|
922 | public: |
---|
923 | |
---|
924 | /// Constructor. |
---|
925 | DfsWizard() : TR() {} |
---|
926 | |
---|
927 | /// Constructor that requires parameters. |
---|
928 | |
---|
929 | /// Constructor that requires parameters. |
---|
930 | /// These parameters will be the default values for the traits class. |
---|
931 | /// \param g The digraph the algorithm runs on. |
---|
932 | DfsWizard(const Digraph &g) : |
---|
933 | TR(g) {} |
---|
934 | |
---|
935 | ///Copy constructor |
---|
936 | DfsWizard(const TR &b) : TR(b) {} |
---|
937 | |
---|
938 | ~DfsWizard() {} |
---|
939 | |
---|
940 | ///Runs DFS algorithm from the given source node. |
---|
941 | |
---|
942 | ///This method runs DFS algorithm from node \c s |
---|
943 | ///in order to compute the DFS path to each node. |
---|
944 | void run(Node s) |
---|
945 | { |
---|
946 | Dfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g)); |
---|
947 | if (Base::_pred) |
---|
948 | alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred)); |
---|
949 | if (Base::_dist) |
---|
950 | alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist)); |
---|
951 | if (Base::_reached) |
---|
952 | alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached)); |
---|
953 | if (Base::_processed) |
---|
954 | alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed)); |
---|
955 | if (s!=INVALID) |
---|
956 | alg.run(s); |
---|
957 | else |
---|
958 | alg.run(); |
---|
959 | } |
---|
960 | |
---|
961 | ///Finds the DFS path between \c s and \c t. |
---|
962 | |
---|
963 | ///This method runs DFS algorithm from node \c s |
---|
964 | ///in order to compute the DFS path to node \c t |
---|
965 | ///(it stops searching when \c t is processed). |
---|
966 | /// |
---|
967 | ///\return \c true if \c t is reachable form \c s. |
---|
968 | bool run(Node s, Node t) |
---|
969 | { |
---|
970 | Dfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g)); |
---|
971 | if (Base::_pred) |
---|
972 | alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred)); |
---|
973 | if (Base::_dist) |
---|
974 | alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist)); |
---|
975 | if (Base::_reached) |
---|
976 | alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached)); |
---|
977 | if (Base::_processed) |
---|
978 | alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed)); |
---|
979 | alg.run(s,t); |
---|
980 | if (Base::_path) |
---|
981 | *reinterpret_cast<Path*>(Base::_path) = alg.path(t); |
---|
982 | if (Base::_di) |
---|
983 | *Base::_di = alg.dist(t); |
---|
984 | return alg.reached(t); |
---|
985 | } |
---|
986 | |
---|
987 | ///Runs DFS algorithm to visit all nodes in the digraph. |
---|
988 | |
---|
989 | ///This method runs DFS algorithm in order to compute |
---|
990 | ///the DFS path to each node. |
---|
991 | void run() |
---|
992 | { |
---|
993 | run(INVALID); |
---|
994 | } |
---|
995 | |
---|
996 | template<class T> |
---|
997 | struct SetPredMapBase : public Base { |
---|
998 | typedef T PredMap; |
---|
999 | static PredMap *createPredMap(const Digraph &) { return 0; }; |
---|
1000 | SetPredMapBase(const TR &b) : TR(b) {} |
---|
1001 | }; |
---|
1002 | ///\brief \ref named-func-param "Named parameter" |
---|
1003 | ///for setting PredMap object. |
---|
1004 | /// |
---|
1005 | ///\ref named-func-param "Named parameter" |
---|
1006 | ///for setting PredMap object. |
---|
1007 | template<class T> |
---|
1008 | DfsWizard<SetPredMapBase<T> > predMap(const T &t) |
---|
1009 | { |
---|
1010 | Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
1011 | return DfsWizard<SetPredMapBase<T> >(*this); |
---|
1012 | } |
---|
1013 | |
---|
1014 | template<class T> |
---|
1015 | struct SetReachedMapBase : public Base { |
---|
1016 | typedef T ReachedMap; |
---|
1017 | static ReachedMap *createReachedMap(const Digraph &) { return 0; }; |
---|
1018 | SetReachedMapBase(const TR &b) : TR(b) {} |
---|
1019 | }; |
---|
1020 | ///\brief \ref named-func-param "Named parameter" |
---|
1021 | ///for setting ReachedMap object. |
---|
1022 | /// |
---|
1023 | /// \ref named-func-param "Named parameter" |
---|
1024 | ///for setting ReachedMap object. |
---|
1025 | template<class T> |
---|
1026 | DfsWizard<SetReachedMapBase<T> > reachedMap(const T &t) |
---|
1027 | { |
---|
1028 | Base::_reached=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
1029 | return DfsWizard<SetReachedMapBase<T> >(*this); |
---|
1030 | } |
---|
1031 | |
---|
1032 | template<class T> |
---|
1033 | struct SetDistMapBase : public Base { |
---|
1034 | typedef T DistMap; |
---|
1035 | static DistMap *createDistMap(const Digraph &) { return 0; }; |
---|
1036 | SetDistMapBase(const TR &b) : TR(b) {} |
---|
1037 | }; |
---|
1038 | ///\brief \ref named-func-param "Named parameter" |
---|
1039 | ///for setting DistMap object. |
---|
1040 | /// |
---|
1041 | /// \ref named-func-param "Named parameter" |
---|
1042 | ///for setting DistMap object. |
---|
1043 | template<class T> |
---|
1044 | DfsWizard<SetDistMapBase<T> > distMap(const T &t) |
---|
1045 | { |
---|
1046 | Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
1047 | return DfsWizard<SetDistMapBase<T> >(*this); |
---|
1048 | } |
---|
1049 | |
---|
1050 | template<class T> |
---|
1051 | struct SetProcessedMapBase : public Base { |
---|
1052 | typedef T ProcessedMap; |
---|
1053 | static ProcessedMap *createProcessedMap(const Digraph &) { return 0; }; |
---|
1054 | SetProcessedMapBase(const TR &b) : TR(b) {} |
---|
1055 | }; |
---|
1056 | ///\brief \ref named-func-param "Named parameter" |
---|
1057 | ///for setting ProcessedMap object. |
---|
1058 | /// |
---|
1059 | /// \ref named-func-param "Named parameter" |
---|
1060 | ///for setting ProcessedMap object. |
---|
1061 | template<class T> |
---|
1062 | DfsWizard<SetProcessedMapBase<T> > processedMap(const T &t) |
---|
1063 | { |
---|
1064 | Base::_processed=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
1065 | return DfsWizard<SetProcessedMapBase<T> >(*this); |
---|
1066 | } |
---|
1067 | |
---|
1068 | template<class T> |
---|
1069 | struct SetPathBase : public Base { |
---|
1070 | typedef T Path; |
---|
1071 | SetPathBase(const TR &b) : TR(b) {} |
---|
1072 | }; |
---|
1073 | ///\brief \ref named-func-param "Named parameter" |
---|
1074 | ///for getting the DFS path to the target node. |
---|
1075 | /// |
---|
1076 | ///\ref named-func-param "Named parameter" |
---|
1077 | ///for getting the DFS path to the target node. |
---|
1078 | template<class T> |
---|
1079 | DfsWizard<SetPathBase<T> > path(const T &t) |
---|
1080 | { |
---|
1081 | Base::_path=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
1082 | return DfsWizard<SetPathBase<T> >(*this); |
---|
1083 | } |
---|
1084 | |
---|
1085 | ///\brief \ref named-func-param "Named parameter" |
---|
1086 | ///for getting the distance of the target node. |
---|
1087 | /// |
---|
1088 | ///\ref named-func-param "Named parameter" |
---|
1089 | ///for getting the distance of the target node. |
---|
1090 | DfsWizard dist(const int &d) |
---|
1091 | { |
---|
1092 | Base::_di=const_cast<int*>(&d); |
---|
1093 | return *this; |
---|
1094 | } |
---|
1095 | |
---|
1096 | }; |
---|
1097 | |
---|
1098 | ///Function-type interface for DFS algorithm. |
---|
1099 | |
---|
1100 | ///\ingroup search |
---|
1101 | ///Function-type interface for DFS algorithm. |
---|
1102 | /// |
---|
1103 | ///This function also has several \ref named-func-param "named parameters", |
---|
1104 | ///they are declared as the members of class \ref DfsWizard. |
---|
1105 | ///The following examples show how to use these parameters. |
---|
1106 | ///\code |
---|
1107 | /// // Compute the DFS tree |
---|
1108 | /// dfs(g).predMap(preds).distMap(dists).run(s); |
---|
1109 | /// |
---|
1110 | /// // Compute the DFS path from s to t |
---|
1111 | /// bool reached = dfs(g).path(p).dist(d).run(s,t); |
---|
1112 | ///\endcode |
---|
1113 | ///\warning Don't forget to put the \ref DfsWizard::run(Node) "run()" |
---|
1114 | ///to the end of the parameter list. |
---|
1115 | ///\sa DfsWizard |
---|
1116 | ///\sa Dfs |
---|
1117 | template<class GR> |
---|
1118 | DfsWizard<DfsWizardBase<GR> > |
---|
1119 | dfs(const GR &digraph) |
---|
1120 | { |
---|
1121 | return DfsWizard<DfsWizardBase<GR> >(digraph); |
---|
1122 | } |
---|
1123 | |
---|
1124 | #ifdef DOXYGEN |
---|
1125 | /// \brief Visitor class for DFS. |
---|
1126 | /// |
---|
1127 | /// This class defines the interface of the DfsVisit events, and |
---|
1128 | /// it could be the base of a real visitor class. |
---|
1129 | template <typename GR> |
---|
1130 | struct DfsVisitor { |
---|
1131 | typedef GR Digraph; |
---|
1132 | typedef typename Digraph::Arc Arc; |
---|
1133 | typedef typename Digraph::Node Node; |
---|
1134 | /// \brief Called for the source node of the DFS. |
---|
1135 | /// |
---|
1136 | /// This function is called for the source node of the DFS. |
---|
1137 | void start(const Node& node) {} |
---|
1138 | /// \brief Called when the source node is leaved. |
---|
1139 | /// |
---|
1140 | /// This function is called when the source node is leaved. |
---|
1141 | void stop(const Node& node) {} |
---|
1142 | /// \brief Called when a node is reached first time. |
---|
1143 | /// |
---|
1144 | /// This function is called when a node is reached first time. |
---|
1145 | void reach(const Node& node) {} |
---|
1146 | /// \brief Called when an arc reaches a new node. |
---|
1147 | /// |
---|
1148 | /// This function is called when the DFS finds an arc whose target node |
---|
1149 | /// is not reached yet. |
---|
1150 | void discover(const Arc& arc) {} |
---|
1151 | /// \brief Called when an arc is examined but its target node is |
---|
1152 | /// already discovered. |
---|
1153 | /// |
---|
1154 | /// This function is called when an arc is examined but its target node is |
---|
1155 | /// already discovered. |
---|
1156 | void examine(const Arc& arc) {} |
---|
1157 | /// \brief Called when the DFS steps back from a node. |
---|
1158 | /// |
---|
1159 | /// This function is called when the DFS steps back from a node. |
---|
1160 | void leave(const Node& node) {} |
---|
1161 | /// \brief Called when the DFS steps back on an arc. |
---|
1162 | /// |
---|
1163 | /// This function is called when the DFS steps back on an arc. |
---|
1164 | void backtrack(const Arc& arc) {} |
---|
1165 | }; |
---|
1166 | #else |
---|
1167 | template <typename GR> |
---|
1168 | struct DfsVisitor { |
---|
1169 | typedef GR Digraph; |
---|
1170 | typedef typename Digraph::Arc Arc; |
---|
1171 | typedef typename Digraph::Node Node; |
---|
1172 | void start(const Node&) {} |
---|
1173 | void stop(const Node&) {} |
---|
1174 | void reach(const Node&) {} |
---|
1175 | void discover(const Arc&) {} |
---|
1176 | void examine(const Arc&) {} |
---|
1177 | void leave(const Node&) {} |
---|
1178 | void backtrack(const Arc&) {} |
---|
1179 | |
---|
1180 | template <typename _Visitor> |
---|
1181 | struct Constraints { |
---|
1182 | void constraints() { |
---|
1183 | Arc arc; |
---|
1184 | Node node; |
---|
1185 | visitor.start(node); |
---|
1186 | visitor.stop(arc); |
---|
1187 | visitor.reach(node); |
---|
1188 | visitor.discover(arc); |
---|
1189 | visitor.examine(arc); |
---|
1190 | visitor.leave(node); |
---|
1191 | visitor.backtrack(arc); |
---|
1192 | } |
---|
1193 | _Visitor& visitor; |
---|
1194 | }; |
---|
1195 | }; |
---|
1196 | #endif |
---|
1197 | |
---|
1198 | /// \brief Default traits class of DfsVisit class. |
---|
1199 | /// |
---|
1200 | /// Default traits class of DfsVisit class. |
---|
1201 | /// \tparam _Digraph The type of the digraph the algorithm runs on. |
---|
1202 | template<class GR> |
---|
1203 | struct DfsVisitDefaultTraits { |
---|
1204 | |
---|
1205 | /// \brief The type of the digraph the algorithm runs on. |
---|
1206 | typedef GR Digraph; |
---|
1207 | |
---|
1208 | /// \brief The type of the map that indicates which nodes are reached. |
---|
1209 | /// |
---|
1210 | /// The type of the map that indicates which nodes are reached. |
---|
1211 | /// It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept. |
---|
1212 | typedef typename Digraph::template NodeMap<bool> ReachedMap; |
---|
1213 | |
---|
1214 | /// \brief Instantiates a ReachedMap. |
---|
1215 | /// |
---|
1216 | /// This function instantiates a ReachedMap. |
---|
1217 | /// \param digraph is the digraph, to which |
---|
1218 | /// we would like to define the ReachedMap. |
---|
1219 | static ReachedMap *createReachedMap(const Digraph &digraph) { |
---|
1220 | return new ReachedMap(digraph); |
---|
1221 | } |
---|
1222 | |
---|
1223 | }; |
---|
1224 | |
---|
1225 | /// \ingroup search |
---|
1226 | /// |
---|
1227 | /// \brief DFS algorithm class with visitor interface. |
---|
1228 | /// |
---|
1229 | /// This class provides an efficient implementation of the DFS algorithm |
---|
1230 | /// with visitor interface. |
---|
1231 | /// |
---|
1232 | /// The DfsVisit class provides an alternative interface to the Dfs |
---|
1233 | /// class. It works with callback mechanism, the DfsVisit object calls |
---|
1234 | /// the member functions of the \c Visitor class on every DFS event. |
---|
1235 | /// |
---|
1236 | /// This interface of the DFS algorithm should be used in special cases |
---|
1237 | /// when extra actions have to be performed in connection with certain |
---|
1238 | /// events of the DFS algorithm. Otherwise consider to use Dfs or dfs() |
---|
1239 | /// instead. |
---|
1240 | /// |
---|
1241 | /// \tparam GR The type of the digraph the algorithm runs on. |
---|
1242 | /// The default type is \ref ListDigraph. |
---|
1243 | /// The value of GR is not used directly by \ref DfsVisit, |
---|
1244 | /// it is only passed to \ref DfsVisitDefaultTraits. |
---|
1245 | /// \tparam VS The Visitor type that is used by the algorithm. |
---|
1246 | /// \ref DfsVisitor "DfsVisitor<GR>" is an empty visitor, which |
---|
1247 | /// does not observe the DFS events. If you want to observe the DFS |
---|
1248 | /// events, you should implement your own visitor class. |
---|
1249 | /// \tparam TR Traits class to set various data types used by the |
---|
1250 | /// algorithm. The default traits class is |
---|
1251 | /// \ref DfsVisitDefaultTraits "DfsVisitDefaultTraits<GR>". |
---|
1252 | /// See \ref DfsVisitDefaultTraits for the documentation of |
---|
1253 | /// a DFS visit traits class. |
---|
1254 | #ifdef DOXYGEN |
---|
1255 | template <typename GR, typename VS, typename TR> |
---|
1256 | #else |
---|
1257 | template <typename GR = ListDigraph, |
---|
1258 | typename VS = DfsVisitor<GR>, |
---|
1259 | typename TR = DfsVisitDefaultTraits<GR> > |
---|
1260 | #endif |
---|
1261 | class DfsVisit { |
---|
1262 | public: |
---|
1263 | |
---|
1264 | ///The traits class. |
---|
1265 | typedef TR Traits; |
---|
1266 | |
---|
1267 | ///The type of the digraph the algorithm runs on. |
---|
1268 | typedef typename Traits::Digraph Digraph; |
---|
1269 | |
---|
1270 | ///The visitor type used by the algorithm. |
---|
1271 | typedef VS Visitor; |
---|
1272 | |
---|
1273 | ///The type of the map that indicates which nodes are reached. |
---|
1274 | typedef typename Traits::ReachedMap ReachedMap; |
---|
1275 | |
---|
1276 | private: |
---|
1277 | |
---|
1278 | typedef typename Digraph::Node Node; |
---|
1279 | typedef typename Digraph::NodeIt NodeIt; |
---|
1280 | typedef typename Digraph::Arc Arc; |
---|
1281 | typedef typename Digraph::OutArcIt OutArcIt; |
---|
1282 | |
---|
1283 | //Pointer to the underlying digraph. |
---|
1284 | const Digraph *_digraph; |
---|
1285 | //Pointer to the visitor object. |
---|
1286 | Visitor *_visitor; |
---|
1287 | //Pointer to the map of reached status of the nodes. |
---|
1288 | ReachedMap *_reached; |
---|
1289 | //Indicates if _reached is locally allocated (true) or not. |
---|
1290 | bool local_reached; |
---|
1291 | |
---|
1292 | std::vector<typename Digraph::Arc> _stack; |
---|
1293 | int _stack_head; |
---|
1294 | |
---|
1295 | //Creates the maps if necessary. |
---|
1296 | void create_maps() { |
---|
1297 | if(!_reached) { |
---|
1298 | local_reached = true; |
---|
1299 | _reached = Traits::createReachedMap(*_digraph); |
---|
1300 | } |
---|
1301 | } |
---|
1302 | |
---|
1303 | protected: |
---|
1304 | |
---|
1305 | DfsVisit() {} |
---|
1306 | |
---|
1307 | public: |
---|
1308 | |
---|
1309 | typedef DfsVisit Create; |
---|
1310 | |
---|
1311 | /// \name Named Template Parameters |
---|
1312 | |
---|
1313 | ///@{ |
---|
1314 | template <class T> |
---|
1315 | struct SetReachedMapTraits : public Traits { |
---|
1316 | typedef T ReachedMap; |
---|
1317 | static ReachedMap *createReachedMap(const Digraph &digraph) { |
---|
1318 | LEMON_ASSERT(false, "ReachedMap is not initialized"); |
---|
1319 | return 0; // ignore warnings |
---|
1320 | } |
---|
1321 | }; |
---|
1322 | /// \brief \ref named-templ-param "Named parameter" for setting |
---|
1323 | /// ReachedMap type. |
---|
1324 | /// |
---|
1325 | /// \ref named-templ-param "Named parameter" for setting ReachedMap type. |
---|
1326 | template <class T> |
---|
1327 | struct SetReachedMap : public DfsVisit< Digraph, Visitor, |
---|
1328 | SetReachedMapTraits<T> > { |
---|
1329 | typedef DfsVisit< Digraph, Visitor, SetReachedMapTraits<T> > Create; |
---|
1330 | }; |
---|
1331 | ///@} |
---|
1332 | |
---|
1333 | public: |
---|
1334 | |
---|
1335 | /// \brief Constructor. |
---|
1336 | /// |
---|
1337 | /// Constructor. |
---|
1338 | /// |
---|
1339 | /// \param digraph The digraph the algorithm runs on. |
---|
1340 | /// \param visitor The visitor object of the algorithm. |
---|
1341 | DfsVisit(const Digraph& digraph, Visitor& visitor) |
---|
1342 | : _digraph(&digraph), _visitor(&visitor), |
---|
1343 | _reached(0), local_reached(false) {} |
---|
1344 | |
---|
1345 | /// \brief Destructor. |
---|
1346 | ~DfsVisit() { |
---|
1347 | if(local_reached) delete _reached; |
---|
1348 | } |
---|
1349 | |
---|
1350 | /// \brief Sets the map that indicates which nodes are reached. |
---|
1351 | /// |
---|
1352 | /// Sets the map that indicates which nodes are reached. |
---|
1353 | /// If you don't use this function before calling \ref run(Node) "run()" |
---|
1354 | /// or \ref init(), an instance will be allocated automatically. |
---|
1355 | /// The destructor deallocates this automatically allocated map, |
---|
1356 | /// of course. |
---|
1357 | /// \return <tt> (*this) </tt> |
---|
1358 | DfsVisit &reachedMap(ReachedMap &m) { |
---|
1359 | if(local_reached) { |
---|
1360 | delete _reached; |
---|
1361 | local_reached=false; |
---|
1362 | } |
---|
1363 | _reached = &m; |
---|
1364 | return *this; |
---|
1365 | } |
---|
1366 | |
---|
1367 | public: |
---|
1368 | |
---|
1369 | /// \name Execution Control |
---|
1370 | /// The simplest way to execute the DFS algorithm is to use one of the |
---|
1371 | /// member functions called \ref run(Node) "run()".\n |
---|
1372 | /// If you need more control on the execution, first you have to call |
---|
1373 | /// \ref init(), then you can add a source node with \ref addSource() |
---|
1374 | /// and perform the actual computation with \ref start(). |
---|
1375 | /// This procedure can be repeated if there are nodes that have not |
---|
1376 | /// been reached. |
---|
1377 | |
---|
1378 | /// @{ |
---|
1379 | |
---|
1380 | /// \brief Initializes the internal data structures. |
---|
1381 | /// |
---|
1382 | /// Initializes the internal data structures. |
---|
1383 | void init() { |
---|
1384 | create_maps(); |
---|
1385 | _stack.resize(countNodes(*_digraph)); |
---|
1386 | _stack_head = -1; |
---|
1387 | for (NodeIt u(*_digraph) ; u != INVALID ; ++u) { |
---|
1388 | _reached->set(u, false); |
---|
1389 | } |
---|
1390 | } |
---|
1391 | |
---|
1392 | /// \brief Adds a new source node. |
---|
1393 | /// |
---|
1394 | /// Adds a new source node to the set of nodes to be processed. |
---|
1395 | /// |
---|
1396 | /// \pre The stack must be empty. Otherwise the algorithm gives |
---|
1397 | /// wrong results. (One of the outgoing arcs of all the source nodes |
---|
1398 | /// except for the last one will not be visited and distances will |
---|
1399 | /// also be wrong.) |
---|
1400 | void addSource(Node s) |
---|
1401 | { |
---|
1402 | LEMON_DEBUG(emptyQueue(), "The stack is not empty."); |
---|
1403 | if(!(*_reached)[s]) { |
---|
1404 | _reached->set(s,true); |
---|
1405 | _visitor->start(s); |
---|
1406 | _visitor->reach(s); |
---|
1407 | Arc e; |
---|
1408 | _digraph->firstOut(e, s); |
---|
1409 | if (e != INVALID) { |
---|
1410 | _stack[++_stack_head] = e; |
---|
1411 | } else { |
---|
1412 | _visitor->leave(s); |
---|
1413 | _visitor->stop(s); |
---|
1414 | } |
---|
1415 | } |
---|
1416 | } |
---|
1417 | |
---|
1418 | /// \brief Processes the next arc. |
---|
1419 | /// |
---|
1420 | /// Processes the next arc. |
---|
1421 | /// |
---|
1422 | /// \return The processed arc. |
---|
1423 | /// |
---|
1424 | /// \pre The stack must not be empty. |
---|
1425 | Arc processNextArc() { |
---|
1426 | Arc e = _stack[_stack_head]; |
---|
1427 | Node m = _digraph->target(e); |
---|
1428 | if(!(*_reached)[m]) { |
---|
1429 | _visitor->discover(e); |
---|
1430 | _visitor->reach(m); |
---|
1431 | _reached->set(m, true); |
---|
1432 | _digraph->firstOut(_stack[++_stack_head], m); |
---|
1433 | } else { |
---|
1434 | _visitor->examine(e); |
---|
1435 | m = _digraph->source(e); |
---|
1436 | _digraph->nextOut(_stack[_stack_head]); |
---|
1437 | } |
---|
1438 | while (_stack_head>=0 && _stack[_stack_head] == INVALID) { |
---|
1439 | _visitor->leave(m); |
---|
1440 | --_stack_head; |
---|
1441 | if (_stack_head >= 0) { |
---|
1442 | _visitor->backtrack(_stack[_stack_head]); |
---|
1443 | m = _digraph->source(_stack[_stack_head]); |
---|
1444 | _digraph->nextOut(_stack[_stack_head]); |
---|
1445 | } else { |
---|
1446 | _visitor->stop(m); |
---|
1447 | } |
---|
1448 | } |
---|
1449 | return e; |
---|
1450 | } |
---|
1451 | |
---|
1452 | /// \brief Next arc to be processed. |
---|
1453 | /// |
---|
1454 | /// Next arc to be processed. |
---|
1455 | /// |
---|
1456 | /// \return The next arc to be processed or INVALID if the stack is |
---|
1457 | /// empty. |
---|
1458 | Arc nextArc() const { |
---|
1459 | return _stack_head >= 0 ? _stack[_stack_head] : INVALID; |
---|
1460 | } |
---|
1461 | |
---|
1462 | /// \brief Returns \c false if there are nodes |
---|
1463 | /// to be processed. |
---|
1464 | /// |
---|
1465 | /// Returns \c false if there are nodes |
---|
1466 | /// to be processed in the queue (stack). |
---|
1467 | bool emptyQueue() const { return _stack_head < 0; } |
---|
1468 | |
---|
1469 | /// \brief Returns the number of the nodes to be processed. |
---|
1470 | /// |
---|
1471 | /// Returns the number of the nodes to be processed in the queue (stack). |
---|
1472 | int queueSize() const { return _stack_head + 1; } |
---|
1473 | |
---|
1474 | /// \brief Executes the algorithm. |
---|
1475 | /// |
---|
1476 | /// Executes the algorithm. |
---|
1477 | /// |
---|
1478 | /// This method runs the %DFS algorithm from the root node |
---|
1479 | /// in order to compute the %DFS path to each node. |
---|
1480 | /// |
---|
1481 | /// The algorithm computes |
---|
1482 | /// - the %DFS tree, |
---|
1483 | /// - the distance of each node from the root in the %DFS tree. |
---|
1484 | /// |
---|
1485 | /// \pre init() must be called and a root node should be |
---|
1486 | /// added with addSource() before using this function. |
---|
1487 | /// |
---|
1488 | /// \note <tt>d.start()</tt> is just a shortcut of the following code. |
---|
1489 | /// \code |
---|
1490 | /// while ( !d.emptyQueue() ) { |
---|
1491 | /// d.processNextArc(); |
---|
1492 | /// } |
---|
1493 | /// \endcode |
---|
1494 | void start() { |
---|
1495 | while ( !emptyQueue() ) processNextArc(); |
---|
1496 | } |
---|
1497 | |
---|
1498 | /// \brief Executes the algorithm until the given target node is reached. |
---|
1499 | /// |
---|
1500 | /// Executes the algorithm until the given target node is reached. |
---|
1501 | /// |
---|
1502 | /// This method runs the %DFS algorithm from the root node |
---|
1503 | /// in order to compute the DFS path to \c t. |
---|
1504 | /// |
---|
1505 | /// The algorithm computes |
---|
1506 | /// - the %DFS path to \c t, |
---|
1507 | /// - the distance of \c t from the root in the %DFS tree. |
---|
1508 | /// |
---|
1509 | /// \pre init() must be called and a root node should be added |
---|
1510 | /// with addSource() before using this function. |
---|
1511 | void start(Node t) { |
---|
1512 | while ( !emptyQueue() && _digraph->target(_stack[_stack_head]) != t ) |
---|
1513 | processNextArc(); |
---|
1514 | } |
---|
1515 | |
---|
1516 | /// \brief Executes the algorithm until a condition is met. |
---|
1517 | /// |
---|
1518 | /// Executes the algorithm until a condition is met. |
---|
1519 | /// |
---|
1520 | /// This method runs the %DFS algorithm from the root node |
---|
1521 | /// until an arc \c a with <tt>am[a]</tt> true is found. |
---|
1522 | /// |
---|
1523 | /// \param am A \c bool (or convertible) arc map. The algorithm |
---|
1524 | /// will stop when it reaches an arc \c a with <tt>am[a]</tt> true. |
---|
1525 | /// |
---|
1526 | /// \return The reached arc \c a with <tt>am[a]</tt> true or |
---|
1527 | /// \c INVALID if no such arc was found. |
---|
1528 | /// |
---|
1529 | /// \pre init() must be called and a root node should be added |
---|
1530 | /// with addSource() before using this function. |
---|
1531 | /// |
---|
1532 | /// \warning Contrary to \ref Bfs and \ref Dijkstra, \c am is an arc map, |
---|
1533 | /// not a node map. |
---|
1534 | template <typename AM> |
---|
1535 | Arc start(const AM &am) { |
---|
1536 | while ( !emptyQueue() && !am[_stack[_stack_head]] ) |
---|
1537 | processNextArc(); |
---|
1538 | return emptyQueue() ? INVALID : _stack[_stack_head]; |
---|
1539 | } |
---|
1540 | |
---|
1541 | /// \brief Runs the algorithm from the given source node. |
---|
1542 | /// |
---|
1543 | /// This method runs the %DFS algorithm from node \c s. |
---|
1544 | /// in order to compute the DFS path to each node. |
---|
1545 | /// |
---|
1546 | /// The algorithm computes |
---|
1547 | /// - the %DFS tree, |
---|
1548 | /// - the distance of each node from the root in the %DFS tree. |
---|
1549 | /// |
---|
1550 | /// \note <tt>d.run(s)</tt> is just a shortcut of the following code. |
---|
1551 | ///\code |
---|
1552 | /// d.init(); |
---|
1553 | /// d.addSource(s); |
---|
1554 | /// d.start(); |
---|
1555 | ///\endcode |
---|
1556 | void run(Node s) { |
---|
1557 | init(); |
---|
1558 | addSource(s); |
---|
1559 | start(); |
---|
1560 | } |
---|
1561 | |
---|
1562 | /// \brief Finds the %DFS path between \c s and \c t. |
---|
1563 | |
---|
1564 | /// This method runs the %DFS algorithm from node \c s |
---|
1565 | /// in order to compute the DFS path to node \c t |
---|
1566 | /// (it stops searching when \c t is processed). |
---|
1567 | /// |
---|
1568 | /// \return \c true if \c t is reachable form \c s. |
---|
1569 | /// |
---|
1570 | /// \note Apart from the return value, <tt>d.run(s,t)</tt> is |
---|
1571 | /// just a shortcut of the following code. |
---|
1572 | ///\code |
---|
1573 | /// d.init(); |
---|
1574 | /// d.addSource(s); |
---|
1575 | /// d.start(t); |
---|
1576 | ///\endcode |
---|
1577 | bool run(Node s,Node t) { |
---|
1578 | init(); |
---|
1579 | addSource(s); |
---|
1580 | start(t); |
---|
1581 | return reached(t); |
---|
1582 | } |
---|
1583 | |
---|
1584 | /// \brief Runs the algorithm to visit all nodes in the digraph. |
---|
1585 | |
---|
1586 | /// This method runs the %DFS algorithm in order to |
---|
1587 | /// compute the %DFS path to each node. |
---|
1588 | /// |
---|
1589 | /// The algorithm computes |
---|
1590 | /// - the %DFS tree (forest), |
---|
1591 | /// - the distance of each node from the root(s) in the %DFS tree. |
---|
1592 | /// |
---|
1593 | /// \note <tt>d.run()</tt> is just a shortcut of the following code. |
---|
1594 | ///\code |
---|
1595 | /// d.init(); |
---|
1596 | /// for (NodeIt n(digraph); n != INVALID; ++n) { |
---|
1597 | /// if (!d.reached(n)) { |
---|
1598 | /// d.addSource(n); |
---|
1599 | /// d.start(); |
---|
1600 | /// } |
---|
1601 | /// } |
---|
1602 | ///\endcode |
---|
1603 | void run() { |
---|
1604 | init(); |
---|
1605 | for (NodeIt it(*_digraph); it != INVALID; ++it) { |
---|
1606 | if (!reached(it)) { |
---|
1607 | addSource(it); |
---|
1608 | start(); |
---|
1609 | } |
---|
1610 | } |
---|
1611 | } |
---|
1612 | |
---|
1613 | ///@} |
---|
1614 | |
---|
1615 | /// \name Query Functions |
---|
1616 | /// The results of the DFS algorithm can be obtained using these |
---|
1617 | /// functions.\n |
---|
1618 | /// Either \ref run(Node) "run()" or \ref start() should be called |
---|
1619 | /// before using them. |
---|
1620 | |
---|
1621 | ///@{ |
---|
1622 | |
---|
1623 | /// \brief Checks if a node is reached from the root(s). |
---|
1624 | /// |
---|
1625 | /// Returns \c true if \c v is reached from the root(s). |
---|
1626 | /// |
---|
1627 | /// \pre Either \ref run(Node) "run()" or \ref init() |
---|
1628 | /// must be called before using this function. |
---|
1629 | bool reached(Node v) const { return (*_reached)[v]; } |
---|
1630 | |
---|
1631 | ///@} |
---|
1632 | |
---|
1633 | }; |
---|
1634 | |
---|
1635 | } //END OF NAMESPACE LEMON |
---|
1636 | |
---|
1637 | #endif |
---|