1 | /* -*- C++ -*- |
---|
2 | * lemon/unionfind.h - Part of LEMON, a generic C++ optimization library |
---|
3 | * |
---|
4 | * Copyright (C) 2006 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
---|
5 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
---|
6 | * |
---|
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. |
---|
10 | * |
---|
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 |
---|
13 | * purpose. |
---|
14 | * |
---|
15 | */ |
---|
16 | |
---|
17 | #ifndef LEMON_UNION_FIND_H |
---|
18 | #define LEMON_UNION_FIND_H |
---|
19 | |
---|
20 | //!\ingroup auxdat |
---|
21 | //!\file |
---|
22 | //!\brief Union-Find data structures. |
---|
23 | //! |
---|
24 | |
---|
25 | #include <vector> |
---|
26 | #include <list> |
---|
27 | #include <utility> |
---|
28 | #include <algorithm> |
---|
29 | |
---|
30 | #include <lemon/invalid.h> |
---|
31 | |
---|
32 | namespace lemon { |
---|
33 | |
---|
34 | //! \addtogroup auxdat |
---|
35 | //! @{ |
---|
36 | |
---|
37 | /** |
---|
38 | * \brief A \e Union-Find data structure implementation |
---|
39 | * |
---|
40 | * The class implements the \e Union-Find data structure. |
---|
41 | * The union operation uses rank heuristic, while |
---|
42 | * the find operation uses path compression. |
---|
43 | * This is a very simple but efficient implementation, providing |
---|
44 | * only four methods: join (union), find, insert and size. |
---|
45 | * For more features see the \ref UnionFindEnum class. |
---|
46 | * |
---|
47 | * It is primarily used in Kruskal algorithm for finding minimal |
---|
48 | * cost spanning tree in a graph. |
---|
49 | * \sa kruskal() |
---|
50 | * |
---|
51 | * \pre The elements are automatically added only if the map |
---|
52 | * given to the constructor was filled with -1's. Otherwise you |
---|
53 | * need to add all the elements by the \ref insert() method. |
---|
54 | * \bug It is not clear what the constructor parameter is used for. |
---|
55 | */ |
---|
56 | |
---|
57 | template <typename T, typename TIntMap> |
---|
58 | class UnionFind { |
---|
59 | |
---|
60 | public: |
---|
61 | typedef T ElementType; |
---|
62 | typedef std::pair<int,int> PairType; |
---|
63 | |
---|
64 | private: |
---|
65 | std::vector<PairType> data; |
---|
66 | TIntMap& map; |
---|
67 | |
---|
68 | public: |
---|
69 | UnionFind(TIntMap& m) : map(m) {} |
---|
70 | |
---|
71 | /** |
---|
72 | * \brief Returns the index of the element's component. |
---|
73 | * |
---|
74 | * The method returns the index of the element's component. |
---|
75 | * This is an integer between zero and the number of inserted elements. |
---|
76 | */ |
---|
77 | |
---|
78 | int find(T a) |
---|
79 | { |
---|
80 | int comp0 = map[a]; |
---|
81 | if (comp0 < 0) { |
---|
82 | return insert(a); |
---|
83 | } |
---|
84 | int comp = comp0; |
---|
85 | int next; |
---|
86 | while ( (next = data[comp].first) != comp) { |
---|
87 | comp = next; |
---|
88 | } |
---|
89 | while ( (next = data[comp0].first) != comp) { |
---|
90 | data[comp0].first = comp; |
---|
91 | comp0 = next; |
---|
92 | } |
---|
93 | |
---|
94 | return comp; |
---|
95 | } |
---|
96 | |
---|
97 | /** |
---|
98 | * \brief Inserts a new element into the structure. |
---|
99 | * |
---|
100 | * This method inserts a new element into the data structure. |
---|
101 | * |
---|
102 | * It is not required to use this method: |
---|
103 | * if the map given to the constructor was filled |
---|
104 | * with -1's then it is called automatically |
---|
105 | * on the first \ref find or \ref join. |
---|
106 | * |
---|
107 | * The method returns the index of the new component. |
---|
108 | */ |
---|
109 | |
---|
110 | int insert(T a) |
---|
111 | { |
---|
112 | int n = data.size(); |
---|
113 | data.push_back(std::make_pair(n, 1)); |
---|
114 | map.set(a,n); |
---|
115 | return n; |
---|
116 | } |
---|
117 | |
---|
118 | /** |
---|
119 | * \brief Joining the components of element \e a and element \e b. |
---|
120 | * |
---|
121 | * This is the \e union operation of the Union-Find structure. |
---|
122 | * Joins the component of element \e a and component of |
---|
123 | * element \e b. If \e a and \e b are in the same component then |
---|
124 | * it returns false otherwise it returns true. |
---|
125 | */ |
---|
126 | |
---|
127 | bool join(T a, T b) |
---|
128 | { |
---|
129 | int ca = find(a); |
---|
130 | int cb = find(b); |
---|
131 | |
---|
132 | if ( ca == cb ) |
---|
133 | return false; |
---|
134 | |
---|
135 | if ( data[ca].second > data[cb].second ) { |
---|
136 | data[cb].first = ca; |
---|
137 | data[ca].second += data[cb].second; |
---|
138 | } |
---|
139 | else { |
---|
140 | data[ca].first = cb; |
---|
141 | data[cb].second += data[ca].second; |
---|
142 | } |
---|
143 | return true; |
---|
144 | } |
---|
145 | |
---|
146 | /** |
---|
147 | * \brief Returns the size of the component of element \e a. |
---|
148 | * |
---|
149 | * Returns the size of the component of element \e a. |
---|
150 | */ |
---|
151 | |
---|
152 | int size(T a) |
---|
153 | { |
---|
154 | int ca = find(a); |
---|
155 | return data[ca].second; |
---|
156 | } |
---|
157 | |
---|
158 | }; |
---|
159 | |
---|
160 | |
---|
161 | |
---|
162 | |
---|
163 | /*******************************************************/ |
---|
164 | |
---|
165 | |
---|
166 | #ifdef DEVELOPMENT_DOCS |
---|
167 | |
---|
168 | /** |
---|
169 | * \brief The auxiliary class for the \ref UnionFindEnum class. |
---|
170 | * |
---|
171 | * In the \ref UnionFindEnum class all components are represented as |
---|
172 | * a std::list. |
---|
173 | * Items of these lists are UnionFindEnumItem structures. |
---|
174 | * |
---|
175 | * The class has four fields: |
---|
176 | * - T me - the actual element |
---|
177 | * - IIter parent - the parent of the element in the union-find structure |
---|
178 | * - int size - the size of the component of the element. |
---|
179 | * Only valid if the element |
---|
180 | * is the leader of the component. |
---|
181 | * - CIter my_class - pointer into the list of components |
---|
182 | * pointing to the component of the element. |
---|
183 | * Only valid if the element is the leader of the component. |
---|
184 | */ |
---|
185 | |
---|
186 | #endif |
---|
187 | |
---|
188 | template <typename T> |
---|
189 | struct UnionFindEnumItem { |
---|
190 | |
---|
191 | typedef std::list<UnionFindEnumItem> ItemList; |
---|
192 | typedef std::list<ItemList> ClassList; |
---|
193 | typedef typename ItemList::iterator IIter; |
---|
194 | typedef typename ClassList::iterator CIter; |
---|
195 | |
---|
196 | T me; |
---|
197 | IIter parent; |
---|
198 | int size; |
---|
199 | CIter my_class; |
---|
200 | |
---|
201 | UnionFindEnumItem() {} |
---|
202 | UnionFindEnumItem(const T &_me, CIter _my_class): |
---|
203 | me(_me), size(1), my_class(_my_class) {} |
---|
204 | }; |
---|
205 | |
---|
206 | |
---|
207 | /** |
---|
208 | * \brief A \e Union-Find data structure implementation which |
---|
209 | * is able to enumerate the components. |
---|
210 | * |
---|
211 | * The class implements a \e Union-Find data structure |
---|
212 | * which is able to enumerate the components and the items in |
---|
213 | * a component. If you don't need this feature then perhaps it's |
---|
214 | * better to use the \ref UnionFind class which is more efficient. |
---|
215 | * |
---|
216 | * The union operation uses rank heuristic, while |
---|
217 | * the find operation uses path compression. |
---|
218 | * |
---|
219 | * \pre You |
---|
220 | * need to add all the elements by the \ref insert() method. |
---|
221 | */ |
---|
222 | |
---|
223 | |
---|
224 | template <typename T, template <typename Item> class Map> |
---|
225 | class UnionFindEnum { |
---|
226 | |
---|
227 | typedef std::list<UnionFindEnumItem<T> > ItemList; |
---|
228 | typedef std::list<ItemList> ClassList; |
---|
229 | typedef typename ItemList::iterator IIter; |
---|
230 | typedef typename ItemList::const_iterator IcIter; |
---|
231 | typedef typename ClassList::iterator CIter; |
---|
232 | typedef typename ClassList::const_iterator CcIter; |
---|
233 | |
---|
234 | public: |
---|
235 | typedef T ElementType; |
---|
236 | typedef UnionFindEnumItem<T> ItemType; |
---|
237 | typedef Map< IIter > MapType; |
---|
238 | |
---|
239 | private: |
---|
240 | MapType& m; |
---|
241 | ClassList classes; |
---|
242 | |
---|
243 | IIter _find(IIter a) const { |
---|
244 | IIter comp = a; |
---|
245 | IIter next; |
---|
246 | while( (next = comp->parent) != comp ) { |
---|
247 | comp = next; |
---|
248 | } |
---|
249 | |
---|
250 | IIter comp1 = a; |
---|
251 | while( (next = comp1->parent) != comp ) { |
---|
252 | comp1->parent = comp->parent; |
---|
253 | comp1 = next; |
---|
254 | } |
---|
255 | return comp; |
---|
256 | } |
---|
257 | |
---|
258 | public: |
---|
259 | UnionFindEnum(MapType& _m) : m(_m) {} |
---|
260 | |
---|
261 | |
---|
262 | /** |
---|
263 | * \brief Inserts the given element into a new component. |
---|
264 | * |
---|
265 | * This method creates a new component consisting only of the |
---|
266 | * given element. |
---|
267 | */ |
---|
268 | |
---|
269 | void insert(const T &a) |
---|
270 | { |
---|
271 | |
---|
272 | |
---|
273 | classes.push_back(ItemList()); |
---|
274 | CIter aclass = classes.end(); |
---|
275 | --aclass; |
---|
276 | |
---|
277 | ItemList &alist = *aclass; |
---|
278 | alist.push_back(ItemType(a, aclass)); |
---|
279 | IIter ai = alist.begin(); |
---|
280 | |
---|
281 | ai->parent = ai; |
---|
282 | m.set(a, ai); |
---|
283 | |
---|
284 | } |
---|
285 | |
---|
286 | /** |
---|
287 | * \brief Inserts the given element into the component of the others. |
---|
288 | * |
---|
289 | * This methods inserts the element \e a into the component of the |
---|
290 | * element \e comp. |
---|
291 | */ |
---|
292 | |
---|
293 | void insert(const T &a, const T &comp) { |
---|
294 | |
---|
295 | IIter clit = _find(m[comp]); |
---|
296 | ItemList &c = *clit->my_class; |
---|
297 | c.push_back(ItemType(a,0)); |
---|
298 | IIter ai = c.end(); |
---|
299 | --ai; |
---|
300 | ai->parent = clit; |
---|
301 | m.set(a, ai); |
---|
302 | ++clit->size; |
---|
303 | } |
---|
304 | |
---|
305 | |
---|
306 | /** |
---|
307 | * \brief Finds the leader of the component of the given element. |
---|
308 | * |
---|
309 | * The method returns the leader of the component of the given element. |
---|
310 | */ |
---|
311 | |
---|
312 | T find(const T &a) const { |
---|
313 | return _find(m[a])->me; |
---|
314 | } |
---|
315 | |
---|
316 | |
---|
317 | /** |
---|
318 | * \brief Joining the component of element \e a and element \e b. |
---|
319 | * |
---|
320 | * This is the \e union operation of the Union-Find structure. |
---|
321 | * Joins the component of element \e a and component of |
---|
322 | * element \e b. If \e a and \e b are in the same component then |
---|
323 | * returns false else returns true. |
---|
324 | */ |
---|
325 | |
---|
326 | bool join(T a, T b) { |
---|
327 | |
---|
328 | IIter ca = _find(m[a]); |
---|
329 | IIter cb = _find(m[b]); |
---|
330 | |
---|
331 | if ( ca == cb ) { |
---|
332 | return false; |
---|
333 | } |
---|
334 | |
---|
335 | if ( ca->size > cb->size ) { |
---|
336 | |
---|
337 | cb->parent = ca->parent; |
---|
338 | ca->size += cb->size; |
---|
339 | |
---|
340 | ItemList &alist = *ca->my_class; |
---|
341 | alist.splice(alist.end(),*cb->my_class); |
---|
342 | |
---|
343 | classes.erase(cb->my_class); |
---|
344 | cb->my_class = 0; |
---|
345 | } |
---|
346 | else { |
---|
347 | |
---|
348 | ca->parent = cb->parent; |
---|
349 | cb->size += ca->size; |
---|
350 | |
---|
351 | ItemList &blist = *cb->my_class; |
---|
352 | blist.splice(blist.end(),*ca->my_class); |
---|
353 | |
---|
354 | classes.erase(ca->my_class); |
---|
355 | ca->my_class = 0; |
---|
356 | } |
---|
357 | |
---|
358 | return true; |
---|
359 | } |
---|
360 | |
---|
361 | |
---|
362 | /** |
---|
363 | * \brief Returns the size of the component of element \e a. |
---|
364 | * |
---|
365 | * Returns the size of the component of element \e a. |
---|
366 | */ |
---|
367 | |
---|
368 | int size(const T &a) const { |
---|
369 | return _find(m[a])->size; |
---|
370 | } |
---|
371 | |
---|
372 | |
---|
373 | /** |
---|
374 | * \brief Splits up the component of the element. |
---|
375 | * |
---|
376 | * Splitting the component of the element into sigleton |
---|
377 | * components (component of size one). |
---|
378 | */ |
---|
379 | |
---|
380 | void split(const T &a) { |
---|
381 | |
---|
382 | IIter ca = _find(m[a]); |
---|
383 | |
---|
384 | if ( ca->size == 1 ) |
---|
385 | return; |
---|
386 | |
---|
387 | CIter aclass = ca->my_class; |
---|
388 | |
---|
389 | for(IIter curr = ca; ++curr != aclass->end(); curr=ca) { |
---|
390 | classes.push_back(ItemList()); |
---|
391 | CIter nl = --classes.end(); |
---|
392 | nl->splice(nl->end(), *aclass, curr); |
---|
393 | |
---|
394 | curr->size=1; |
---|
395 | curr->parent=curr; |
---|
396 | curr->my_class = nl; |
---|
397 | } |
---|
398 | |
---|
399 | ca->size=1; |
---|
400 | return; |
---|
401 | } |
---|
402 | |
---|
403 | |
---|
404 | /** |
---|
405 | * \brief Sets the given element to the leader element of its component. |
---|
406 | * |
---|
407 | * Sets the given element to the leader element of its component. |
---|
408 | */ |
---|
409 | |
---|
410 | void makeRep(const T &a) { |
---|
411 | |
---|
412 | IIter ia = m[a]; |
---|
413 | IIter la = _find(ia); |
---|
414 | if (la == ia) return; |
---|
415 | |
---|
416 | ia->my_class = la->my_class; |
---|
417 | la->my_class = 0; |
---|
418 | |
---|
419 | ia->size = la->size; |
---|
420 | |
---|
421 | CIter l = ia->my_class; |
---|
422 | l->splice(l->begin(),*l,ia); |
---|
423 | |
---|
424 | ia->parent = ia; |
---|
425 | la->parent = ia; |
---|
426 | } |
---|
427 | |
---|
428 | /** |
---|
429 | * \brief Moves the given element to an other component. |
---|
430 | * |
---|
431 | * This method moves the element \e a from its component |
---|
432 | * to the component of \e comp. |
---|
433 | * If \e a and \e comp are in the same component then |
---|
434 | * it returns false otherwise it returns true. |
---|
435 | */ |
---|
436 | |
---|
437 | bool move(const T &a, const T &comp) { |
---|
438 | |
---|
439 | IIter ai = m[a]; |
---|
440 | IIter lai = _find(ai); |
---|
441 | IIter clit = _find(m[comp]); |
---|
442 | |
---|
443 | if (lai == clit) |
---|
444 | return false; |
---|
445 | |
---|
446 | ItemList &cl = *clit->my_class, |
---|
447 | &al = *lai->my_class; |
---|
448 | |
---|
449 | bool is_leader = (lai == ai); |
---|
450 | bool singleton = false; |
---|
451 | |
---|
452 | if (is_leader) { |
---|
453 | ++lai; |
---|
454 | } |
---|
455 | |
---|
456 | cl.splice(cl.end(), al, ai); |
---|
457 | |
---|
458 | if (is_leader) { |
---|
459 | if (ai->size == 1) { |
---|
460 | classes.erase(ai->my_class); |
---|
461 | singleton = true; |
---|
462 | } |
---|
463 | else { |
---|
464 | lai->size = ai->size; |
---|
465 | lai->my_class = ai->my_class; |
---|
466 | } |
---|
467 | } |
---|
468 | if (!singleton) { |
---|
469 | for (IIter i = lai; i != al.end(); ++i) |
---|
470 | i->parent = lai; |
---|
471 | --lai->size; |
---|
472 | } |
---|
473 | |
---|
474 | ai->parent = clit; |
---|
475 | ai->my_class = 0; |
---|
476 | ++clit->size; |
---|
477 | |
---|
478 | return true; |
---|
479 | } |
---|
480 | |
---|
481 | |
---|
482 | /** |
---|
483 | * \brief Removes the given element from the structure. |
---|
484 | * |
---|
485 | * Removes the given element from the structure. |
---|
486 | * |
---|
487 | * Removes the element from its component and if the component becomes |
---|
488 | * empty then removes that component from the component list. |
---|
489 | */ |
---|
490 | void erase(const T &a) { |
---|
491 | |
---|
492 | IIter ma = m[a]; |
---|
493 | if (ma == 0) return; |
---|
494 | |
---|
495 | IIter la = _find(ma); |
---|
496 | if (la == ma) { |
---|
497 | if (ma -> size == 1){ |
---|
498 | classes.erase(ma->my_class); |
---|
499 | m.set(a,0); |
---|
500 | return; |
---|
501 | } |
---|
502 | ++la; |
---|
503 | la->size = ma->size; |
---|
504 | la->my_class = ma->my_class; |
---|
505 | } |
---|
506 | |
---|
507 | for (IIter i = la; i != la->my_class->end(); ++i) { |
---|
508 | i->parent = la; |
---|
509 | } |
---|
510 | |
---|
511 | la->size--; |
---|
512 | la->my_class->erase(ma); |
---|
513 | m.set(a,0); |
---|
514 | } |
---|
515 | |
---|
516 | /** |
---|
517 | * \brief Removes the component of the given element from the structure. |
---|
518 | * |
---|
519 | * Removes the component of the given element from the structure. |
---|
520 | */ |
---|
521 | |
---|
522 | void eraseClass(const T &a) { |
---|
523 | IIter ma = m[a]; |
---|
524 | if (ma == 0) return; |
---|
525 | # ifdef DEBUG |
---|
526 | CIter c = _find(ma)->my_class; |
---|
527 | for (IIter i=c->begin(); i!=c->end(); ++i) |
---|
528 | m.set(i->me, 0); |
---|
529 | # endif |
---|
530 | classes.erase(_find(ma)->my_class); |
---|
531 | } |
---|
532 | |
---|
533 | |
---|
534 | class ClassIt { |
---|
535 | friend class UnionFindEnum; |
---|
536 | |
---|
537 | CcIter i; |
---|
538 | public: |
---|
539 | ClassIt(Invalid): i(0) {} |
---|
540 | ClassIt() {} |
---|
541 | |
---|
542 | operator const T& () const { |
---|
543 | ItemList const &ll = *i; |
---|
544 | return (ll.begin())->me; } |
---|
545 | bool operator == (ClassIt it) const { |
---|
546 | return (i == it.i); |
---|
547 | } |
---|
548 | bool operator != (ClassIt it) const { |
---|
549 | return (i != it.i); |
---|
550 | } |
---|
551 | bool operator < (ClassIt it) const { |
---|
552 | return (i < it.i); |
---|
553 | } |
---|
554 | |
---|
555 | bool valid() const { return i != 0; } |
---|
556 | private: |
---|
557 | void first(const ClassList &l) { i = l.begin(); validate(l); } |
---|
558 | void next(const ClassList &l) { |
---|
559 | ++i; |
---|
560 | validate(l); |
---|
561 | } |
---|
562 | void validate(const ClassList &l) { |
---|
563 | if ( i == l.end() ) |
---|
564 | i = 0; |
---|
565 | } |
---|
566 | }; |
---|
567 | |
---|
568 | /** |
---|
569 | * \brief Sets the iterator to point to the first component. |
---|
570 | * |
---|
571 | * Sets the iterator to point to the first component. |
---|
572 | * |
---|
573 | * With the \ref first, \ref valid and \ref next methods you can |
---|
574 | * iterate through the components. For example: |
---|
575 | * \code |
---|
576 | * UnionFindEnum<Graph::Node, Graph::NodeMap>::MapType map(G); |
---|
577 | * UnionFindEnum<Graph::Node, Graph::NodeMap> U(map); |
---|
578 | * UnionFindEnum<Graph::Node, Graph::NodeMap>::ClassIt iter; |
---|
579 | * for (U.first(iter); U.valid(iter); U.next(iter)) { |
---|
580 | * // iter is convertible to Graph::Node |
---|
581 | * cout << iter << endl; |
---|
582 | * } |
---|
583 | * \endcode |
---|
584 | */ |
---|
585 | |
---|
586 | ClassIt& first(ClassIt& it) const { |
---|
587 | it.first(classes); |
---|
588 | return it; |
---|
589 | } |
---|
590 | |
---|
591 | /** |
---|
592 | * \brief Returns whether the iterator is valid. |
---|
593 | * |
---|
594 | * Returns whether the iterator is valid. |
---|
595 | * |
---|
596 | * With the \ref first, \ref valid and \ref next methods you can |
---|
597 | * iterate through the components. See the example here: \ref first. |
---|
598 | */ |
---|
599 | |
---|
600 | bool valid(ClassIt const &it) const { |
---|
601 | return it.valid(); |
---|
602 | } |
---|
603 | |
---|
604 | /** |
---|
605 | * \brief Steps the iterator to the next component. |
---|
606 | * |
---|
607 | * Steps the iterator to the next component. |
---|
608 | * |
---|
609 | * With the \ref first, \ref valid and \ref next methods you can |
---|
610 | * iterate through the components. See the example here: \ref first. |
---|
611 | */ |
---|
612 | |
---|
613 | ClassIt& next(ClassIt& it) const { |
---|
614 | it.next(classes); |
---|
615 | return it; |
---|
616 | } |
---|
617 | |
---|
618 | |
---|
619 | class ItemIt { |
---|
620 | friend class UnionFindEnum; |
---|
621 | |
---|
622 | IcIter i; |
---|
623 | const ItemList *l; |
---|
624 | public: |
---|
625 | ItemIt(Invalid): i(0) {} |
---|
626 | ItemIt() {} |
---|
627 | |
---|
628 | operator const T& () const { return i->me; } |
---|
629 | bool operator == (ItemIt it) const { |
---|
630 | return (i == it.i); |
---|
631 | } |
---|
632 | bool operator != (ItemIt it) const { |
---|
633 | return (i != it.i); |
---|
634 | } |
---|
635 | bool operator < (ItemIt it) const { |
---|
636 | return (i < it.i); |
---|
637 | } |
---|
638 | |
---|
639 | bool valid() const { return i != 0; } |
---|
640 | private: |
---|
641 | void first(const ItemList &il) { l=&il; i = l->begin(); validate(); } |
---|
642 | void next() { |
---|
643 | ++i; |
---|
644 | validate(); |
---|
645 | } |
---|
646 | void validate() { |
---|
647 | if ( i == l->end() ) |
---|
648 | i = 0; |
---|
649 | } |
---|
650 | }; |
---|
651 | |
---|
652 | |
---|
653 | |
---|
654 | /** |
---|
655 | * \brief Sets the iterator to point to the first element of the component. |
---|
656 | * |
---|
657 | * \anchor first2 |
---|
658 | * Sets the iterator to point to the first element of the component. |
---|
659 | * |
---|
660 | * With the \ref first2 "first", \ref valid2 "valid" |
---|
661 | * and \ref next2 "next" methods you can |
---|
662 | * iterate through the elements of a component. For example |
---|
663 | * (iterating through the component of the node \e node): |
---|
664 | * \code |
---|
665 | * Graph::Node node = ...; |
---|
666 | * UnionFindEnum<Graph::Node, Graph::NodeMap>::MapType map(G); |
---|
667 | * UnionFindEnum<Graph::Node, Graph::NodeMap> U(map); |
---|
668 | * UnionFindEnum<Graph::Node, Graph::NodeMap>::ItemIt iiter; |
---|
669 | * for (U.first(iiter, node); U.valid(iiter); U.next(iiter)) { |
---|
670 | * // iiter is convertible to Graph::Node |
---|
671 | * cout << iiter << endl; |
---|
672 | * } |
---|
673 | * \endcode |
---|
674 | */ |
---|
675 | |
---|
676 | ItemIt& first(ItemIt& it, const T& a) const { |
---|
677 | it.first( * _find(m[a])->my_class ); |
---|
678 | return it; |
---|
679 | } |
---|
680 | |
---|
681 | /** |
---|
682 | * \brief Returns whether the iterator is valid. |
---|
683 | * |
---|
684 | * \anchor valid2 |
---|
685 | * Returns whether the iterator is valid. |
---|
686 | * |
---|
687 | * With the \ref first2 "first", \ref valid2 "valid" |
---|
688 | * and \ref next2 "next" methods you can |
---|
689 | * iterate through the elements of a component. |
---|
690 | * See the example here: \ref first2 "first". |
---|
691 | */ |
---|
692 | |
---|
693 | bool valid(ItemIt const &it) const { |
---|
694 | return it.valid(); |
---|
695 | } |
---|
696 | |
---|
697 | /** |
---|
698 | * \brief Steps the iterator to the next component. |
---|
699 | * |
---|
700 | * \anchor next2 |
---|
701 | * Steps the iterator to the next component. |
---|
702 | * |
---|
703 | * With the \ref first2 "first", \ref valid2 "valid" |
---|
704 | * and \ref next2 "next" methods you can |
---|
705 | * iterate through the elements of a component. |
---|
706 | * See the example here: \ref first2 "first". |
---|
707 | */ |
---|
708 | |
---|
709 | ItemIt& next(ItemIt& it) const { |
---|
710 | it.next(); |
---|
711 | return it; |
---|
712 | } |
---|
713 | |
---|
714 | }; |
---|
715 | |
---|
716 | |
---|
717 | //! @} |
---|
718 | |
---|
719 | } //namespace lemon |
---|
720 | |
---|
721 | #endif //LEMON_UNION_FIND_H |
---|