forked from KolibriOS/kolibrios
487 lines
11 KiB
C
487 lines
11 KiB
C
/* A Fibonacci heap datatype.
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Copyright 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
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Contributed by Daniel Berlin (dan@cgsoftware.com).
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 51 Franklin Street - Fifth Floor,
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Boston, MA 02110-1301, USA. */
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#ifdef HAVE_LIMITS_H
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#include <limits.h>
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#endif
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#ifdef HAVE_STDLIB_H
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#include <stdlib.h>
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#endif
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#ifdef HAVE_STRING_H
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#include <string.h>
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#endif
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#include "libiberty.h"
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#include "fibheap.h"
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#define FIBHEAPKEY_MIN LONG_MIN
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static void fibheap_ins_root (fibheap_t, fibnode_t);
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static void fibheap_rem_root (fibheap_t, fibnode_t);
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static void fibheap_consolidate (fibheap_t);
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static void fibheap_link (fibheap_t, fibnode_t, fibnode_t);
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static void fibheap_cut (fibheap_t, fibnode_t, fibnode_t);
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static void fibheap_cascading_cut (fibheap_t, fibnode_t);
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static fibnode_t fibheap_extr_min_node (fibheap_t);
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static int fibheap_compare (fibheap_t, fibnode_t, fibnode_t);
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static int fibheap_comp_data (fibheap_t, fibheapkey_t, void *, fibnode_t);
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static fibnode_t fibnode_new (void);
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static void fibnode_insert_after (fibnode_t, fibnode_t);
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#define fibnode_insert_before(a, b) fibnode_insert_after (a->left, b)
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static fibnode_t fibnode_remove (fibnode_t);
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/* Create a new fibonacci heap. */
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fibheap_t
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fibheap_new (void)
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{
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return (fibheap_t) xcalloc (1, sizeof (struct fibheap));
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}
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/* Create a new fibonacci heap node. */
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static fibnode_t
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fibnode_new (void)
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{
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fibnode_t node;
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node = (fibnode_t) xcalloc (1, sizeof *node);
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node->left = node;
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node->right = node;
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return node;
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}
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static inline int
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fibheap_compare (fibheap_t heap ATTRIBUTE_UNUSED, fibnode_t a, fibnode_t b)
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{
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if (a->key < b->key)
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return -1;
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if (a->key > b->key)
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return 1;
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return 0;
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}
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static inline int
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fibheap_comp_data (fibheap_t heap, fibheapkey_t key, void *data, fibnode_t b)
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{
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struct fibnode a;
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a.key = key;
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a.data = data;
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return fibheap_compare (heap, &a, b);
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}
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/* Insert DATA, with priority KEY, into HEAP. */
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fibnode_t
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fibheap_insert (fibheap_t heap, fibheapkey_t key, void *data)
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{
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fibnode_t node;
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/* Create the new node. */
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node = fibnode_new ();
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/* Set the node's data. */
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node->data = data;
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node->key = key;
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/* Insert it into the root list. */
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fibheap_ins_root (heap, node);
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/* If their was no minimum, or this key is less than the min,
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it's the new min. */
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if (heap->min == NULL || node->key < heap->min->key)
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heap->min = node;
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heap->nodes++;
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return node;
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}
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/* Return the data of the minimum node (if we know it). */
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void *
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fibheap_min (fibheap_t heap)
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{
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/* If there is no min, we can't easily return it. */
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if (heap->min == NULL)
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return NULL;
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return heap->min->data;
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}
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/* Return the key of the minimum node (if we know it). */
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fibheapkey_t
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fibheap_min_key (fibheap_t heap)
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{
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/* If there is no min, we can't easily return it. */
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if (heap->min == NULL)
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return 0;
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return heap->min->key;
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}
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/* Union HEAPA and HEAPB into a new heap. */
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fibheap_t
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fibheap_union (fibheap_t heapa, fibheap_t heapb)
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{
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fibnode_t a_root, b_root, temp;
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/* If one of the heaps is empty, the union is just the other heap. */
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if ((a_root = heapa->root) == NULL)
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{
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free (heapa);
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return heapb;
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}
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if ((b_root = heapb->root) == NULL)
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{
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free (heapb);
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return heapa;
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}
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/* Merge them to the next nodes on the opposite chain. */
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a_root->left->right = b_root;
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b_root->left->right = a_root;
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temp = a_root->left;
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a_root->left = b_root->left;
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b_root->left = temp;
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heapa->nodes += heapb->nodes;
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/* And set the new minimum, if it's changed. */
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if (fibheap_compare (heapa, heapb->min, heapa->min) < 0)
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heapa->min = heapb->min;
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free (heapb);
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return heapa;
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}
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/* Extract the data of the minimum node from HEAP. */
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void *
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fibheap_extract_min (fibheap_t heap)
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{
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fibnode_t z;
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void *ret = NULL;
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/* If we don't have a min set, it means we have no nodes. */
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if (heap->min != NULL)
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{
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/* Otherwise, extract the min node, free the node, and return the
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node's data. */
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z = fibheap_extr_min_node (heap);
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ret = z->data;
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free (z);
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}
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return ret;
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}
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/* Replace both the KEY and the DATA associated with NODE. */
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void *
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fibheap_replace_key_data (fibheap_t heap, fibnode_t node,
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fibheapkey_t key, void *data)
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{
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void *odata;
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fibheapkey_t okey;
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fibnode_t y;
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/* If we wanted to, we could actually do a real increase by redeleting and
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inserting. However, this would require O (log n) time. So just bail out
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for now. */
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if (fibheap_comp_data (heap, key, data, node) > 0)
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return NULL;
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odata = node->data;
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okey = node->key;
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node->data = data;
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node->key = key;
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y = node->parent;
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/* Short-circuit if the key is the same, as we then don't have to
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do anything. Except if we're trying to force the new node to
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be the new minimum for delete. */
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if (okey == key && okey != FIBHEAPKEY_MIN)
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return odata;
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/* These two compares are specifically <= 0 to make sure that in the case
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of equality, a node we replaced the data on, becomes the new min. This
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is needed so that delete's call to extractmin gets the right node. */
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if (y != NULL && fibheap_compare (heap, node, y) <= 0)
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{
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fibheap_cut (heap, node, y);
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fibheap_cascading_cut (heap, y);
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}
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if (fibheap_compare (heap, node, heap->min) <= 0)
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heap->min = node;
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return odata;
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}
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/* Replace the DATA associated with NODE. */
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void *
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fibheap_replace_data (fibheap_t heap, fibnode_t node, void *data)
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{
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return fibheap_replace_key_data (heap, node, node->key, data);
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}
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/* Replace the KEY associated with NODE. */
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fibheapkey_t
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fibheap_replace_key (fibheap_t heap, fibnode_t node, fibheapkey_t key)
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{
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int okey = node->key;
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fibheap_replace_key_data (heap, node, key, node->data);
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return okey;
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}
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/* Delete NODE from HEAP. */
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void *
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fibheap_delete_node (fibheap_t heap, fibnode_t node)
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{
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void *ret = node->data;
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/* To perform delete, we just make it the min key, and extract. */
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fibheap_replace_key (heap, node, FIBHEAPKEY_MIN);
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if (node != heap->min)
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{
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fprintf (stderr, "Can't force minimum on fibheap.\n");
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abort ();
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}
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fibheap_extract_min (heap);
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return ret;
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}
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/* Delete HEAP. */
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void
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fibheap_delete (fibheap_t heap)
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{
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while (heap->min != NULL)
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free (fibheap_extr_min_node (heap));
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free (heap);
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}
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/* Determine if HEAP is empty. */
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int
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fibheap_empty (fibheap_t heap)
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{
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return heap->nodes == 0;
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}
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/* Extract the minimum node of the heap. */
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static fibnode_t
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fibheap_extr_min_node (fibheap_t heap)
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{
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fibnode_t ret = heap->min;
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fibnode_t x, y, orig;
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/* Attach the child list of the minimum node to the root list of the heap.
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If there is no child list, we don't do squat. */
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for (x = ret->child, orig = NULL; x != orig && x != NULL; x = y)
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{
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if (orig == NULL)
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orig = x;
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y = x->right;
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x->parent = NULL;
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fibheap_ins_root (heap, x);
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}
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/* Remove the old root. */
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fibheap_rem_root (heap, ret);
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heap->nodes--;
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/* If we are left with no nodes, then the min is NULL. */
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if (heap->nodes == 0)
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heap->min = NULL;
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else
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{
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/* Otherwise, consolidate to find new minimum, as well as do the reorg
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work that needs to be done. */
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heap->min = ret->right;
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fibheap_consolidate (heap);
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}
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return ret;
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}
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/* Insert NODE into the root list of HEAP. */
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static void
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fibheap_ins_root (fibheap_t heap, fibnode_t node)
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{
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/* If the heap is currently empty, the new node becomes the singleton
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circular root list. */
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if (heap->root == NULL)
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{
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heap->root = node;
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node->left = node;
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node->right = node;
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return;
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}
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/* Otherwise, insert it in the circular root list between the root
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and it's right node. */
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fibnode_insert_after (heap->root, node);
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}
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/* Remove NODE from the rootlist of HEAP. */
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static void
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fibheap_rem_root (fibheap_t heap, fibnode_t node)
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{
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if (node->left == node)
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heap->root = NULL;
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else
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heap->root = fibnode_remove (node);
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}
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/* Consolidate the heap. */
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static void
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fibheap_consolidate (fibheap_t heap)
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{
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fibnode_t a[1 + 8 * sizeof (long)];
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fibnode_t w;
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fibnode_t y;
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fibnode_t x;
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int i;
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int d;
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int D;
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D = 1 + 8 * sizeof (long);
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memset (a, 0, sizeof (fibnode_t) * D);
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while ((w = heap->root) != NULL)
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{
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x = w;
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fibheap_rem_root (heap, w);
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d = x->degree;
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while (a[d] != NULL)
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{
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y = a[d];
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if (fibheap_compare (heap, x, y) > 0)
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{
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fibnode_t temp;
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temp = x;
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x = y;
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y = temp;
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}
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fibheap_link (heap, y, x);
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a[d] = NULL;
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d++;
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}
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a[d] = x;
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}
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heap->min = NULL;
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for (i = 0; i < D; i++)
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if (a[i] != NULL)
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{
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fibheap_ins_root (heap, a[i]);
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if (heap->min == NULL || fibheap_compare (heap, a[i], heap->min) < 0)
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heap->min = a[i];
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}
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}
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/* Make NODE a child of PARENT. */
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static void
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fibheap_link (fibheap_t heap ATTRIBUTE_UNUSED,
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fibnode_t node, fibnode_t parent)
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{
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if (parent->child == NULL)
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parent->child = node;
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else
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fibnode_insert_before (parent->child, node);
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node->parent = parent;
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parent->degree++;
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node->mark = 0;
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}
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/* Remove NODE from PARENT's child list. */
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static void
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fibheap_cut (fibheap_t heap, fibnode_t node, fibnode_t parent)
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{
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fibnode_remove (node);
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parent->degree--;
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fibheap_ins_root (heap, node);
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node->parent = NULL;
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node->mark = 0;
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}
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static void
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fibheap_cascading_cut (fibheap_t heap, fibnode_t y)
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{
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fibnode_t z;
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while ((z = y->parent) != NULL)
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{
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if (y->mark == 0)
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{
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y->mark = 1;
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return;
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}
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else
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{
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fibheap_cut (heap, y, z);
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y = z;
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}
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}
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}
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static void
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fibnode_insert_after (fibnode_t a, fibnode_t b)
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{
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if (a == a->right)
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{
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a->right = b;
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a->left = b;
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b->right = a;
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b->left = a;
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}
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else
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{
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b->right = a->right;
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a->right->left = b;
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a->right = b;
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b->left = a;
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}
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}
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static fibnode_t
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fibnode_remove (fibnode_t node)
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{
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fibnode_t ret;
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if (node == node->left)
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ret = NULL;
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else
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ret = node->left;
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if (node->parent != NULL && node->parent->child == node)
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node->parent->child = ret;
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node->right->left = node->left;
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node->left->right = node->right;
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node->parent = NULL;
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node->left = node;
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node->right = node;
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return ret;
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}
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