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ba1a7a0f | 1 | /* Fibonacci heap for GNU compiler. |
a945c346 | 2 | Copyright (C) 1998-2024 Free Software Foundation, Inc. |
4a910049 ML |
3 | Contributed by Daniel Berlin (dan@cgsoftware.com). |
4 | Re-implemented in C++ by Martin Liska <mliska@suse.cz> | |
5 | ||
6 | This file is part of GCC. | |
7 | ||
8 | GCC is free software; you can redistribute it and/or modify it under | |
9 | the terms of the GNU General Public License as published by the Free | |
10 | Software Foundation; either version 3, or (at your option) any later | |
11 | version. | |
12 | ||
13 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
14 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
15 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
16 | for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with GCC; see the file COPYING3. If not see | |
20 | <http://www.gnu.org/licenses/>. */ | |
21 | ||
22 | /* Fibonacci heaps are somewhat complex, but, there's an article in | |
23 | DDJ that explains them pretty well: | |
24 | ||
25 | http://www.ddj.com/articles/1997/9701/9701o/9701o.htm?topic=algoritms | |
26 | ||
27 | Introduction to algorithms by Corman and Rivest also goes over them. | |
28 | ||
29 | The original paper that introduced them is "Fibonacci heaps and their | |
30 | uses in improved network optimization algorithms" by Tarjan and | |
31 | Fredman (JACM 34(3), July 1987). | |
32 | ||
33 | Amortized and real worst case time for operations: | |
34 | ||
35 | ExtractMin: O(lg n) amortized. O(n) worst case. | |
36 | DecreaseKey: O(1) amortized. O(lg n) worst case. | |
37 | Insert: O(1) amortized. | |
38 | Union: O(1) amortized. */ | |
39 | ||
40 | #ifndef GCC_FIBONACCI_HEAP_H | |
41 | #define GCC_FIBONACCI_HEAP_H | |
42 | ||
43 | /* Forward definition. */ | |
44 | ||
45 | template<class K, class V> | |
46 | class fibonacci_heap; | |
47 | ||
48 | /* Fibonacci heap node class. */ | |
49 | ||
50 | template<class K, class V> | |
51 | class fibonacci_node | |
52 | { | |
53 | typedef fibonacci_node<K,V> fibonacci_node_t; | |
54 | friend class fibonacci_heap<K,V>; | |
55 | ||
56 | public: | |
57 | /* Default constructor. */ | |
58 | fibonacci_node (): m_parent (NULL), m_child (NULL), m_left (this), | |
8d509fb6 | 59 | m_right (this), m_data (NULL), m_degree (0), m_mark (0) |
4a910049 ML |
60 | { |
61 | } | |
62 | ||
63 | /* Constructor for a node with given KEY. */ | |
ba1a7a0f ML |
64 | fibonacci_node (K key, V *data = NULL): m_parent (NULL), m_child (NULL), |
65 | m_left (this), m_right (this), m_key (key), m_data (data), | |
4a910049 ML |
66 | m_degree (0), m_mark (0) |
67 | { | |
68 | } | |
69 | ||
70 | /* Compare fibonacci node with OTHER node. */ | |
71 | int compare (fibonacci_node_t *other) | |
72 | { | |
73 | if (m_key < other->m_key) | |
74 | return -1; | |
75 | if (m_key > other->m_key) | |
76 | return 1; | |
77 | return 0; | |
78 | } | |
79 | ||
80 | /* Compare the node with a given KEY. */ | |
81 | int compare_data (K key) | |
82 | { | |
83 | return fibonacci_node_t (key).compare (this); | |
84 | } | |
85 | ||
86 | /* Remove fibonacci heap node. */ | |
87 | fibonacci_node_t *remove (); | |
88 | ||
89 | /* Link the node with PARENT. */ | |
90 | void link (fibonacci_node_t *parent); | |
91 | ||
92 | /* Return key associated with the node. */ | |
93 | K get_key () | |
94 | { | |
95 | return m_key; | |
96 | } | |
97 | ||
98 | /* Return data associated with the node. */ | |
99 | V *get_data () | |
100 | { | |
101 | return m_data; | |
102 | } | |
103 | ||
104 | private: | |
105 | /* Put node B after this node. */ | |
106 | void insert_after (fibonacci_node_t *b); | |
107 | ||
108 | /* Insert fibonacci node B after this node. */ | |
109 | void insert_before (fibonacci_node_t *b) | |
110 | { | |
111 | m_left->insert_after (b); | |
112 | } | |
113 | ||
114 | /* Parent node. */ | |
115 | fibonacci_node *m_parent; | |
116 | /* Child node. */ | |
117 | fibonacci_node *m_child; | |
118 | /* Left sibling. */ | |
119 | fibonacci_node *m_left; | |
120 | /* Right node. */ | |
121 | fibonacci_node *m_right; | |
122 | /* Key associated with node. */ | |
123 | K m_key; | |
124 | /* Data associated with node. */ | |
125 | V *m_data; | |
126 | ||
127 | #if defined (__GNUC__) && (!defined (SIZEOF_INT) || SIZEOF_INT < 4) | |
128 | /* Degree of the node. */ | |
129 | __extension__ unsigned long int m_degree : 31; | |
130 | /* Mark of the node. */ | |
131 | __extension__ unsigned long int m_mark : 1; | |
132 | #else | |
133 | /* Degree of the node. */ | |
134 | unsigned int m_degree : 31; | |
135 | /* Mark of the node. */ | |
136 | unsigned int m_mark : 1; | |
137 | #endif | |
138 | }; | |
139 | ||
140 | /* Fibonacci heap class. */ | |
141 | template<class K, class V> | |
142 | class fibonacci_heap | |
143 | { | |
144 | typedef fibonacci_node<K,V> fibonacci_node_t; | |
145 | friend class fibonacci_node<K,V>; | |
146 | ||
147 | public: | |
516fd7ce JH |
148 | /* Default constructor. ALLOCATOR is optional and is primarily useful |
149 | when heaps are going to be merged (in that case they need to be allocated | |
150 | in same alloc pool). */ | |
151 | fibonacci_heap (K global_min_key, pool_allocator *allocator = NULL): | |
152 | m_nodes (0), m_min (NULL), m_root (NULL), | |
153 | m_global_min_key (global_min_key), | |
154 | m_allocator (allocator), m_own_allocator (false) | |
4a910049 | 155 | { |
516fd7ce JH |
156 | if (!m_allocator) |
157 | { | |
158 | m_allocator = new pool_allocator ("Fibonacci heap", | |
159 | sizeof (fibonacci_node_t)); | |
160 | m_own_allocator = true; | |
161 | } | |
4a910049 ML |
162 | } |
163 | ||
164 | /* Destructor. */ | |
165 | ~fibonacci_heap () | |
166 | { | |
516fd7ce JH |
167 | /* Actual memory will be released by the destructor of m_allocator. */ |
168 | if (need_finalization_p<fibonacci_node_t> () || !m_own_allocator) | |
169 | while (m_min != NULL) | |
170 | { | |
171 | fibonacci_node_t *n = extract_minimum_node (); | |
172 | n->~fibonacci_node_t (); | |
173 | if (!m_own_allocator) | |
174 | m_allocator->remove (n); | |
175 | } | |
176 | if (m_own_allocator) | |
177 | delete m_allocator; | |
4a910049 ML |
178 | } |
179 | ||
180 | /* Insert new node given by KEY and DATA associated with the key. */ | |
181 | fibonacci_node_t *insert (K key, V *data); | |
182 | ||
183 | /* Return true if no entry is present. */ | |
26a23d11 | 184 | bool empty () const |
4a910049 ML |
185 | { |
186 | return m_nodes == 0; | |
187 | } | |
188 | ||
189 | /* Return the number of nodes. */ | |
26a23d11 | 190 | size_t nodes () const |
4a910049 ML |
191 | { |
192 | return m_nodes; | |
193 | } | |
194 | ||
195 | /* Return minimal key presented in the heap. */ | |
26a23d11 | 196 | K min_key () const |
4a910049 ML |
197 | { |
198 | if (m_min == NULL) | |
199 | gcc_unreachable (); | |
200 | ||
201 | return m_min->m_key; | |
202 | } | |
203 | ||
204 | /* For given NODE, set new KEY value. */ | |
a3dc1a45 | 205 | K replace_key (fibonacci_node_t *node, K key) |
4a910049 ML |
206 | { |
207 | K okey = node->m_key; | |
4a910049 ML |
208 | |
209 | replace_key_data (node, key, node->m_data); | |
210 | return okey; | |
211 | } | |
212 | ||
a3dc1a45 ML |
213 | /* For given NODE, decrease value to new KEY. */ |
214 | K decrease_key (fibonacci_node_t *node, K key) | |
215 | { | |
216 | gcc_assert (key <= node->m_key); | |
217 | return replace_key (node, key); | |
218 | } | |
219 | ||
4a910049 ML |
220 | /* For given NODE, set new KEY and DATA value. */ |
221 | V *replace_key_data (fibonacci_node_t *node, K key, V *data); | |
222 | ||
a3dc1a45 ML |
223 | /* Extract minimum node in the heap. If RELEASE is specified, |
224 | memory is released. */ | |
225 | V *extract_min (bool release = true); | |
4a910049 ML |
226 | |
227 | /* Return value associated with minimum node in the heap. */ | |
26a23d11 | 228 | V *min () const |
4a910049 ML |
229 | { |
230 | if (m_min == NULL) | |
231 | return NULL; | |
232 | ||
c0f15a3f | 233 | return m_min->m_data; |
4a910049 ML |
234 | } |
235 | ||
236 | /* Replace data associated with NODE and replace it with DATA. */ | |
237 | V *replace_data (fibonacci_node_t *node, V *data) | |
238 | { | |
239 | return replace_key_data (node, node->m_key, data); | |
240 | } | |
241 | ||
242 | /* Delete NODE in the heap. */ | |
a3dc1a45 | 243 | V *delete_node (fibonacci_node_t *node, bool release = true); |
4a910049 ML |
244 | |
245 | /* Union the heap with HEAPB. */ | |
246 | fibonacci_heap *union_with (fibonacci_heap *heapb); | |
247 | ||
248 | private: | |
a3dc1a45 ML |
249 | /* Insert new NODE given by KEY and DATA associated with the key. */ |
250 | fibonacci_node_t *insert (fibonacci_node_t *node, K key, V *data); | |
251 | ||
ba1a7a0f ML |
252 | /* Insert new NODE that has already filled key and value. */ |
253 | fibonacci_node_t *insert_node (fibonacci_node_t *node); | |
254 | ||
4a910049 ML |
255 | /* Insert it into the root list. */ |
256 | void insert_root (fibonacci_node_t *node); | |
257 | ||
258 | /* Remove NODE from PARENT's child list. */ | |
259 | void cut (fibonacci_node_t *node, fibonacci_node_t *parent); | |
260 | ||
261 | /* Process cut of node Y and do it recursivelly. */ | |
262 | void cascading_cut (fibonacci_node_t *y); | |
263 | ||
264 | /* Extract minimum node from the heap. */ | |
265 | fibonacci_node_t * extract_minimum_node (); | |
266 | ||
267 | /* Remove root NODE from the heap. */ | |
268 | void remove_root (fibonacci_node_t *node); | |
269 | ||
270 | /* Consolidate heap. */ | |
271 | void consolidate (); | |
272 | ||
273 | /* Number of nodes. */ | |
274 | size_t m_nodes; | |
275 | /* Minimum node of the heap. */ | |
276 | fibonacci_node_t *m_min; | |
277 | /* Root node of the heap. */ | |
278 | fibonacci_node_t *m_root; | |
279 | /* Global minimum given in the heap construction. */ | |
280 | K m_global_min_key; | |
516fd7ce JH |
281 | |
282 | /* Allocator used to hold nodes. */ | |
283 | pool_allocator *m_allocator; | |
284 | /* True if alocator is owned by the current heap only. */ | |
285 | bool m_own_allocator; | |
4a910049 ML |
286 | }; |
287 | ||
288 | /* Remove fibonacci heap node. */ | |
289 | ||
290 | template<class K, class V> | |
291 | fibonacci_node<K,V> * | |
292 | fibonacci_node<K,V>::remove () | |
293 | { | |
294 | fibonacci_node<K,V> *ret; | |
295 | ||
296 | if (this == m_left) | |
297 | ret = NULL; | |
298 | else | |
299 | ret = m_left; | |
300 | ||
301 | if (m_parent != NULL && m_parent->m_child == this) | |
302 | m_parent->m_child = ret; | |
303 | ||
304 | m_right->m_left = m_left; | |
305 | m_left->m_right = m_right; | |
306 | ||
307 | m_parent = NULL; | |
308 | m_left = this; | |
309 | m_right = this; | |
310 | ||
311 | return ret; | |
312 | } | |
313 | ||
314 | /* Link the node with PARENT. */ | |
315 | ||
316 | template<class K, class V> | |
317 | void | |
318 | fibonacci_node<K,V>::link (fibonacci_node<K,V> *parent) | |
319 | { | |
320 | if (parent->m_child == NULL) | |
321 | parent->m_child = this; | |
322 | else | |
323 | parent->m_child->insert_before (this); | |
324 | m_parent = parent; | |
325 | parent->m_degree++; | |
326 | m_mark = 0; | |
327 | } | |
328 | ||
329 | /* Put node B after this node. */ | |
330 | ||
331 | template<class K, class V> | |
332 | void | |
333 | fibonacci_node<K,V>::insert_after (fibonacci_node<K,V> *b) | |
334 | { | |
335 | fibonacci_node<K,V> *a = this; | |
336 | ||
337 | if (a == a->m_right) | |
338 | { | |
339 | a->m_right = b; | |
340 | a->m_left = b; | |
341 | b->m_right = a; | |
342 | b->m_left = a; | |
343 | } | |
344 | else | |
345 | { | |
346 | b->m_right = a->m_right; | |
347 | a->m_right->m_left = b; | |
348 | a->m_right = b; | |
349 | b->m_left = a; | |
350 | } | |
351 | } | |
352 | ||
353 | /* Insert new node given by KEY and DATA associated with the key. */ | |
354 | ||
355 | template<class K, class V> | |
356 | fibonacci_node<K,V>* | |
357 | fibonacci_heap<K,V>::insert (K key, V *data) | |
358 | { | |
359 | /* Create the new node. */ | |
516fd7ce JH |
360 | fibonacci_node<K,V> *node = new (m_allocator->allocate ()) |
361 | fibonacci_node_t (key, data); | |
4a910049 | 362 | |
ba1a7a0f | 363 | return insert_node (node); |
a3dc1a45 ML |
364 | } |
365 | ||
ba1a7a0f | 366 | /* Insert new NODE given by DATA associated with the key. */ |
a3dc1a45 ML |
367 | |
368 | template<class K, class V> | |
369 | fibonacci_node<K,V>* | |
370 | fibonacci_heap<K,V>::insert (fibonacci_node_t *node, K key, V *data) | |
371 | { | |
4a910049 ML |
372 | /* Set the node's data. */ |
373 | node->m_data = data; | |
374 | node->m_key = key; | |
375 | ||
ba1a7a0f ML |
376 | return insert_node (node); |
377 | } | |
378 | ||
379 | /* Insert new NODE that has already filled key and value. */ | |
380 | ||
381 | template<class K, class V> | |
382 | fibonacci_node<K,V>* | |
383 | fibonacci_heap<K,V>::insert_node (fibonacci_node_t *node) | |
384 | { | |
4a910049 ML |
385 | /* Insert it into the root list. */ |
386 | insert_root (node); | |
387 | ||
388 | /* If their was no minimum, or this key is less than the min, | |
389 | it's the new min. */ | |
390 | if (m_min == NULL || node->m_key < m_min->m_key) | |
391 | m_min = node; | |
392 | ||
393 | m_nodes++; | |
394 | ||
395 | return node; | |
396 | } | |
397 | ||
398 | /* For given NODE, set new KEY and DATA value. */ | |
ba1a7a0f | 399 | |
4a910049 ML |
400 | template<class K, class V> |
401 | V* | |
402 | fibonacci_heap<K,V>::replace_key_data (fibonacci_node<K,V> *node, K key, | |
403 | V *data) | |
404 | { | |
4a910049 ML |
405 | K okey; |
406 | fibonacci_node<K,V> *y; | |
a3dc1a45 | 407 | V *odata = node->m_data; |
4a910049 | 408 | |
a3dc1a45 ML |
409 | /* If we wanted to, we do a real increase by redeleting and |
410 | inserting. */ | |
4a910049 | 411 | if (node->compare_data (key) > 0) |
a3dc1a45 ML |
412 | { |
413 | delete_node (node, false); | |
414 | ||
415 | node = new (node) fibonacci_node_t (); | |
416 | insert (node, key, data); | |
417 | ||
418 | return odata; | |
419 | } | |
4a910049 | 420 | |
4a910049 ML |
421 | okey = node->m_key; |
422 | node->m_data = data; | |
423 | node->m_key = key; | |
424 | y = node->m_parent; | |
425 | ||
426 | /* Short-circuit if the key is the same, as we then don't have to | |
427 | do anything. Except if we're trying to force the new node to | |
428 | be the new minimum for delete. */ | |
429 | if (okey == key && okey != m_global_min_key) | |
430 | return odata; | |
431 | ||
432 | /* These two compares are specifically <= 0 to make sure that in the case | |
433 | of equality, a node we replaced the data on, becomes the new min. This | |
434 | is needed so that delete's call to extractmin gets the right node. */ | |
435 | if (y != NULL && node->compare (y) <= 0) | |
436 | { | |
437 | cut (node, y); | |
438 | cascading_cut (y); | |
439 | } | |
440 | ||
441 | if (node->compare (m_min) <= 0) | |
442 | m_min = node; | |
443 | ||
444 | return odata; | |
445 | } | |
446 | ||
ba1a7a0f ML |
447 | /* Extract minimum node in the heap. Delete fibonacci node if RELEASE |
448 | is true. */ | |
449 | ||
4a910049 ML |
450 | template<class K, class V> |
451 | V* | |
a3dc1a45 | 452 | fibonacci_heap<K,V>::extract_min (bool release) |
4a910049 ML |
453 | { |
454 | fibonacci_node<K,V> *z; | |
455 | V *ret = NULL; | |
456 | ||
457 | /* If we don't have a min set, it means we have no nodes. */ | |
458 | if (m_min != NULL) | |
459 | { | |
460 | /* Otherwise, extract the min node, free the node, and return the | |
461 | node's data. */ | |
462 | z = extract_minimum_node (); | |
463 | ret = z->m_data; | |
a3dc1a45 ML |
464 | |
465 | if (release) | |
516fd7ce JH |
466 | { |
467 | z->~fibonacci_node_t (); | |
468 | m_allocator->remove (z); | |
469 | } | |
4a910049 ML |
470 | } |
471 | ||
472 | return ret; | |
473 | } | |
474 | ||
a3dc1a45 | 475 | /* Delete NODE in the heap, if RELEASE is specified memory is released. */ |
4a910049 ML |
476 | |
477 | template<class K, class V> | |
478 | V* | |
a3dc1a45 | 479 | fibonacci_heap<K,V>::delete_node (fibonacci_node<K,V> *node, bool release) |
4a910049 ML |
480 | { |
481 | V *ret = node->m_data; | |
482 | ||
483 | /* To perform delete, we just make it the min key, and extract. */ | |
a3dc1a45 | 484 | replace_key (node, m_global_min_key); |
4a910049 ML |
485 | if (node != m_min) |
486 | { | |
487 | fprintf (stderr, "Can't force minimum on fibheap.\n"); | |
488 | abort (); | |
489 | } | |
a3dc1a45 | 490 | extract_min (release); |
4a910049 ML |
491 | |
492 | return ret; | |
493 | } | |
494 | ||
ba1a7a0f | 495 | /* Union the heap with HEAPB. One of the heaps is going to be deleted. */ |
4a910049 ML |
496 | |
497 | template<class K, class V> | |
498 | fibonacci_heap<K,V>* | |
499 | fibonacci_heap<K,V>::union_with (fibonacci_heap<K,V> *heapb) | |
500 | { | |
501 | fibonacci_heap<K,V> *heapa = this; | |
502 | ||
fab27f52 | 503 | fibonacci_node<K,V> *a_root, *b_root; |
4a910049 | 504 | |
516fd7ce JH |
505 | /* Both heaps must share allocator. */ |
506 | gcc_checking_assert (m_allocator == heapb->m_allocator); | |
507 | ||
4a910049 ML |
508 | /* If one of the heaps is empty, the union is just the other heap. */ |
509 | if ((a_root = heapa->m_root) == NULL) | |
510 | { | |
511 | delete (heapa); | |
512 | return heapb; | |
513 | } | |
514 | if ((b_root = heapb->m_root) == NULL) | |
515 | { | |
516 | delete (heapb); | |
517 | return heapa; | |
518 | } | |
519 | ||
520 | /* Merge them to the next nodes on the opposite chain. */ | |
521 | a_root->m_left->m_right = b_root; | |
522 | b_root->m_left->m_right = a_root; | |
fab27f52 | 523 | std::swap (a_root->m_left, b_root->m_left); |
4a910049 ML |
524 | heapa->m_nodes += heapb->m_nodes; |
525 | ||
526 | /* And set the new minimum, if it's changed. */ | |
ba1a7a0f | 527 | if (heapb->m_min->compare (heapa->m_min) < 0) |
4a910049 ML |
528 | heapa->m_min = heapb->m_min; |
529 | ||
ba1a7a0f ML |
530 | /* Set m_min to NULL to not to delete live fibonacci nodes. */ |
531 | heapb->m_min = NULL; | |
4a910049 | 532 | delete (heapb); |
ba1a7a0f | 533 | |
4a910049 ML |
534 | return heapa; |
535 | } | |
536 | ||
537 | /* Insert it into the root list. */ | |
538 | ||
539 | template<class K, class V> | |
540 | void | |
541 | fibonacci_heap<K,V>::insert_root (fibonacci_node_t *node) | |
542 | { | |
543 | /* If the heap is currently empty, the new node becomes the singleton | |
544 | circular root list. */ | |
545 | if (m_root == NULL) | |
546 | { | |
547 | m_root = node; | |
548 | node->m_left = node; | |
549 | node->m_right = node; | |
550 | return; | |
551 | } | |
552 | ||
553 | /* Otherwise, insert it in the circular root list between the root | |
554 | and it's right node. */ | |
555 | m_root->insert_after (node); | |
556 | } | |
557 | ||
558 | /* Remove NODE from PARENT's child list. */ | |
559 | ||
560 | template<class K, class V> | |
561 | void | |
562 | fibonacci_heap<K,V>::cut (fibonacci_node<K,V> *node, | |
563 | fibonacci_node<K,V> *parent) | |
564 | { | |
565 | node->remove (); | |
566 | parent->m_degree--; | |
567 | insert_root (node); | |
568 | node->m_parent = NULL; | |
569 | node->m_mark = 0; | |
570 | } | |
571 | ||
572 | /* Process cut of node Y and do it recursivelly. */ | |
573 | ||
574 | template<class K, class V> | |
575 | void | |
576 | fibonacci_heap<K,V>::cascading_cut (fibonacci_node<K,V> *y) | |
577 | { | |
578 | fibonacci_node<K,V> *z; | |
579 | ||
580 | while ((z = y->m_parent) != NULL) | |
581 | { | |
582 | if (y->m_mark == 0) | |
583 | { | |
584 | y->m_mark = 1; | |
585 | return; | |
586 | } | |
587 | else | |
588 | { | |
589 | cut (y, z); | |
590 | y = z; | |
591 | } | |
592 | } | |
593 | } | |
594 | ||
595 | /* Extract minimum node from the heap. */ | |
ba1a7a0f | 596 | |
4a910049 ML |
597 | template<class K, class V> |
598 | fibonacci_node<K,V>* | |
599 | fibonacci_heap<K,V>::extract_minimum_node () | |
600 | { | |
601 | fibonacci_node<K,V> *ret = m_min; | |
602 | fibonacci_node<K,V> *x, *y, *orig; | |
603 | ||
604 | /* Attach the child list of the minimum node to the root list of the heap. | |
605 | If there is no child list, we don't do squat. */ | |
606 | for (x = ret->m_child, orig = NULL; x != orig && x != NULL; x = y) | |
607 | { | |
608 | if (orig == NULL) | |
609 | orig = x; | |
610 | y = x->m_right; | |
611 | x->m_parent = NULL; | |
612 | insert_root (x); | |
613 | } | |
614 | ||
615 | /* Remove the old root. */ | |
616 | remove_root (ret); | |
617 | m_nodes--; | |
618 | ||
619 | /* If we are left with no nodes, then the min is NULL. */ | |
620 | if (m_nodes == 0) | |
621 | m_min = NULL; | |
622 | else | |
623 | { | |
624 | /* Otherwise, consolidate to find new minimum, as well as do the reorg | |
625 | work that needs to be done. */ | |
626 | m_min = ret->m_right; | |
627 | consolidate (); | |
628 | } | |
629 | ||
630 | return ret; | |
631 | } | |
632 | ||
633 | /* Remove root NODE from the heap. */ | |
634 | ||
635 | template<class K, class V> | |
636 | void | |
637 | fibonacci_heap<K,V>::remove_root (fibonacci_node<K,V> *node) | |
638 | { | |
639 | if (node->m_left == node) | |
640 | m_root = NULL; | |
641 | else | |
642 | m_root = node->remove (); | |
643 | } | |
644 | ||
645 | /* Consolidate heap. */ | |
646 | ||
647 | template<class K, class V> | |
648 | void fibonacci_heap<K,V>::consolidate () | |
649 | { | |
516fd7ce | 650 | const int D = 1 + 8 * sizeof (long); |
8e361de1 | 651 | fibonacci_node<K,V> *a[D]; |
4a910049 ML |
652 | fibonacci_node<K,V> *w, *x, *y; |
653 | int i, d; | |
654 | ||
8e361de1 | 655 | memset (a, 0, sizeof (a)); |
516fd7ce | 656 | |
4a910049 ML |
657 | while ((w = m_root) != NULL) |
658 | { | |
659 | x = w; | |
660 | remove_root (w); | |
661 | d = x->m_degree; | |
8e361de1 | 662 | gcc_checking_assert (d < D); |
4a910049 ML |
663 | while (a[d] != NULL) |
664 | { | |
665 | y = a[d]; | |
666 | if (x->compare (y) > 0) | |
667 | std::swap (x, y); | |
668 | y->link (x); | |
669 | a[d] = NULL; | |
670 | d++; | |
671 | } | |
672 | a[d] = x; | |
673 | } | |
674 | m_min = NULL; | |
675 | for (i = 0; i < D; i++) | |
676 | if (a[i] != NULL) | |
677 | { | |
678 | insert_root (a[i]); | |
679 | if (m_min == NULL || a[i]->compare (m_min) < 0) | |
680 | m_min = a[i]; | |
681 | } | |
682 | } | |
683 | ||
684 | #endif // GCC_FIBONACCI_HEAP_H |