1 /* A Fibonacci heap datatype.
2 Copyright 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
3 Contributed by Daniel Berlin (dan@cgsoftware.com).
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
34 #include "libiberty.h"
38 #define FIBHEAPKEY_MIN LONG_MIN
40 static void fibheap_init PARAMS ((fibheap_t));
41 static void fibheap_ins_root PARAMS ((fibheap_t, fibnode_t));
42 static void fibheap_rem_root PARAMS ((fibheap_t, fibnode_t));
43 static void fibheap_consolidate PARAMS ((fibheap_t));
44 static void fibheap_link PARAMS ((fibheap_t, fibnode_t, fibnode_t));
45 static void fibheap_cut PARAMS ((fibheap_t, fibnode_t, fibnode_t));
46 static void fibheap_cascading_cut PARAMS ((fibheap_t, fibnode_t));
47 static fibnode_t fibheap_extr_min_node PARAMS ((fibheap_t));
48 static int fibheap_compare PARAMS ((fibheap_t, fibnode_t, fibnode_t));
49 static int fibheap_comp_data PARAMS ((fibheap_t, fibheapkey_t, void *,
51 static fibnode_t fibnode_new PARAMS ((void));
52 static void fibnode_init PARAMS ((fibnode_t));
53 static void fibnode_insert_after PARAMS ((fibnode_t, fibnode_t));
54 #define fibnode_insert_before(a, b) fibnode_insert_after (a->left, b)
55 static fibnode_t fibnode_remove PARAMS ((fibnode_t));
58 /* Initialize the passed in fibonacci heap. */
68 /* Create a new fibonacci heap. */
74 if ((result = xmalloc (sizeof (*result))) == NULL)
77 fibheap_init (result);
82 /* Initialize the passed in fibonacci heap node. */
96 /* Create a new fibonacci heap node. */
97 static inline fibnode_t
102 if ((e = xmalloc (sizeof *e)) == NULL)
111 fibheap_compare (heap, a, b)
112 fibheap_t heap ATTRIBUTE_UNUSED;
124 fibheap_comp_data (heap, key, data, b)
135 return fibheap_compare (heap, &a, b);
138 /* Insert DATA, with priority KEY, into HEAP. */
140 fibheap_insert (heap, key, data)
147 /* Create the new node, if we fail, return NULL. */
148 if ((node = fibnode_new ()) == NULL)
151 /* Set the node's data. */
155 /* Insert it into the root list. */
156 fibheap_ins_root (heap, node);
158 /* If their was no minimum, or this key is less than the min,
160 if (heap->min == NULL || node->key < heap->min->key)
168 /* Return the data of the minimum node (if we know it). */
173 /* If there is no min, we can't easily return it. */
174 if (heap->min == NULL)
176 return heap->min->data;
179 /* Return the key of the minimum node (if we know it). */
181 fibheap_min_key (heap)
184 /* If there is no min, we can't easily return it. */
185 if (heap->min == NULL)
187 return heap->min->key;
190 /* Union HEAPA and HEAPB into a new heap. */
192 fibheap_union (heapa, heapb)
196 fibnode_t a_root, b_root, temp;
198 /* If one of the heaps is empty, the union is just the other heap. */
199 if ((a_root = heapa->root) == NULL)
204 if ((b_root = heapb->root) == NULL)
210 /* Merge them to the next nodes on the opposite chain. */
211 a_root->left->right = b_root;
212 b_root->left->right = a_root;
214 a_root->left = b_root->left;
216 heapa->nodes += heapb->nodes;
218 /* And set the new minimum, if it's changed. */
219 if (fibheap_compare (heapa, heapb->min, heapa->min) < 0)
220 heapa->min = heapb->min;
226 /* Extract the data of the minimum node from HEAP. */
228 fibheap_extract_min (heap)
234 /* If we don't have a min set, it means we have no nodes. */
235 if (heap->min != NULL)
237 /* Otherwise, extract the min node, free the node, and return the
239 z = fibheap_extr_min_node (heap);
247 /* Replace both the KEY and the DATA associated with NODE. */
249 fibheap_replace_key_data (heap, node, key, data)
259 /* If we wanted to, we could actually do a real increase by redeleting and
260 inserting. However, this would require O (log n) time. So just bail out
262 if (fibheap_comp_data (heap, key, data, node) > 0)
274 /* These two compares are specifically <= 0 to make sure that in the case
275 of equality, a node we replaced the data on, becomes the new min. This
276 is needed so that delete's call to extractmin gets the right node. */
277 if (y != NULL && fibheap_compare (heap, node, y) <= 0)
279 fibheap_cut (heap, node, y);
280 fibheap_cascading_cut (heap, y);
283 if (fibheap_compare (heap, node, heap->min) <= 0)
289 /* Replace the DATA associated with NODE. */
291 fibheap_replace_data (heap, node, data)
296 return fibheap_replace_key_data (heap, node, node->key, data);
299 /* Replace the KEY associated with NODE. */
301 fibheap_replace_key (heap, node, key)
306 int okey = node->key;
307 fibheap_replace_key_data (heap, node, key, node->data);
311 /* Delete NODE from HEAP. */
313 fibheap_delete_node (heap, node)
317 void *ret = node->data;
319 /* To perform delete, we just make it the min key, and extract. */
320 fibheap_replace_key (heap, node, FIBHEAPKEY_MIN);
321 fibheap_extract_min (heap);
328 fibheap_delete (heap)
331 while (heap->min != NULL)
332 free (fibheap_extr_min_node (heap));
337 /* Determine if HEAP is empty. */
342 return heap->nodes == 0;
345 /* Extract the minimum node of the heap. */
347 fibheap_extr_min_node (heap)
350 fibnode_t ret = heap->min;
351 fibnode_t x, y, orig;
353 /* Attach the child list of the minimum node to the root list of the heap.
354 If there is no child list, we don't do squat. */
355 for (x = ret->child, orig = NULL; x != orig && x != NULL; x = y)
361 fibheap_ins_root (heap, x);
364 /* Remove the old root. */
365 fibheap_rem_root (heap, ret);
368 /* If we are left with no nodes, then the min is NULL. */
369 if (heap->nodes == 0)
373 /* Otherwise, consolidate to find new minimum, as well as do the reorg
374 work that needs to be done. */
375 heap->min = ret->right;
376 fibheap_consolidate (heap);
382 /* Insert NODE into the root list of HEAP. */
384 fibheap_ins_root (heap, node)
388 /* If the heap is currently empty, the new node becomes the singleton
389 circular root list. */
390 if (heap->root == NULL)
398 /* Otherwise, insert it in the circular root list between the root
399 and it's right node. */
400 fibnode_insert_after (heap->root, node);
403 /* Remove NODE from the rootlist of HEAP. */
405 fibheap_rem_root (heap, node)
409 if (node->left == node)
412 heap->root = fibnode_remove (node);
415 /* Consolidate the heap. */
417 fibheap_consolidate (heap)
420 fibnode_t a[1 + 8 * sizeof (long)];
428 D = 1 + 8 * sizeof (long);
430 memset (a, 0, sizeof (fibnode_t) * D);
432 while ((w = heap->root) != NULL)
435 fibheap_rem_root (heap, w);
440 if (fibheap_compare (heap, x, y) > 0)
447 fibheap_link (heap, y, x);
454 for (i = 0; i < D; i++)
457 fibheap_ins_root (heap, a[i]);
458 if (heap->min == NULL || fibheap_compare (heap, a[i], heap->min) < 0)
463 /* Make NODE a child of PARENT. */
465 fibheap_link (heap, node, parent)
466 fibheap_t heap ATTRIBUTE_UNUSED;
470 if (parent->child == NULL)
471 parent->child = node;
473 fibnode_insert_before (parent->child, node);
474 node->parent = parent;
479 /* Remove NODE from PARENT's child list. */
481 fibheap_cut (heap, node, parent)
486 fibnode_remove (node);
488 fibheap_ins_root (heap, node);
494 fibheap_cascading_cut (heap, y)
500 while ((z = y->parent) != NULL)
509 fibheap_cut (heap, y, z);
516 fibnode_insert_after (a, b)
537 fibnode_remove (node)
542 if (node == node->left)
547 if (node->parent != NULL && node->parent->child == node)
548 node->parent->child = ret;
550 node->right->left = node->left;
551 node->left->right = node->right;