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/*-
* Copyright 1997-2003 John-Mark Gurney.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id: fib.c,v 1.31 2003/01/14 10:11:30 jmg Exp $
*
*/
#include <fib.h>
#include <fibpriv.h>
#include <limits.h>
#include <stdlib.h>
#define swap(type, a, b) \
do { \
type c; \
c = a; \
a = b; \
b = c; \
} while (0) \
#define INT_BITS (sizeof(int) * 8)
static inline int
ceillog2(unsigned int a)
{
int oa;
int i;
int b;
oa = a;
b = INT_BITS / 2;
i = 0;
while (b) {
i = (i << 1);
if (a >= (1 << b)) {
a /= (1 << b);
i = i | 1;
} else
a &= (1 << b) - 1;
b /= 2;
}
if ((1 << i) == oa)
return i;
else
return i + 1;
}
/*
* Private Heap Functions
*/
static void
fh_deleteel(struct fibheap *h, struct fibheap_el *x)
{
void *data;
int key;
data = x->fhe_data;
key = x->fhe_key;
if (!h->fh_keys)
fh_replacedata(h, x, h->fh_neginf);
else
fh_replacekey(h, x, INT_MIN);
if (fh_extractminel(h) != x) {
/*
* XXX - This should never happen as fh_replace should set it
* to min.
*/
abort();
}
x->fhe_data = data;
x->fhe_key = key;
}
static void
fh_initheap(struct fibheap *new)
{
new->fh_cmp_fnct = NULL;
new->fh_neginf = NULL;
new->fh_n = 0;
new->fh_Dl = -1;
new->fh_cons = NULL;
new->fh_min = NULL;
new->fh_root = NULL;
new->fh_keys = 0;
#ifdef FH_STATS
new->fh_maxn = 0;
new->fh_ninserts = 0;
new->fh_nextracts = 0;
#endif
}
static void
fh_destroyheap(struct fibheap *h)
{
h->fh_cmp_fnct = NULL;
h->fh_neginf = NULL;
if (h->fh_cons != NULL)
free(h->fh_cons);
h->fh_cons = NULL;
free(h);
}
/*
* Public Heap Functions
*/
struct fibheap *
fh_makekeyheap()
{
struct fibheap *n;
if ((n = malloc(sizeof *n)) == NULL)
return NULL;
fh_initheap(n);
n->fh_keys = 1;
return n;
}
struct fibheap *
fh_makeheap()
{
struct fibheap *n;
if ((n = malloc(sizeof *n)) == NULL)
return NULL;
fh_initheap(n);
return n;
}
voidcmp
fh_setcmp(struct fibheap *h, voidcmp fnct)
{
voidcmp oldfnct;
oldfnct = h->fh_cmp_fnct;
h->fh_cmp_fnct = fnct;
return oldfnct;
}
void *
fh_setneginf(struct fibheap *h, void *data)
{
void *old;
old = h->fh_neginf;
h->fh_neginf = data;
return old;
}
struct fibheap *
fh_union(struct fibheap *ha, struct fibheap *hb)
{
struct fibheap_el *x;
if (ha->fh_root == NULL || hb->fh_root == NULL) {
/* either one or both are empty */
if (ha->fh_root == NULL) {
fh_destroyheap(ha);
return hb;
} else {
fh_destroyheap(hb);
return ha;
}
}
ha->fh_root->fhe_left->fhe_right = hb->fh_root;
hb->fh_root->fhe_left->fhe_right = ha->fh_root;
x = ha->fh_root->fhe_left;
ha->fh_root->fhe_left = hb->fh_root->fhe_left;
hb->fh_root->fhe_left = x;
ha->fh_n += hb->fh_n;
/*
* we probably should also keep stats on number of unions
*/
/* set fh_min if necessary */
if (fh_compare(ha, hb->fh_min, ha->fh_min) < 0)
ha->fh_min = hb->fh_min;
fh_destroyheap(hb);
return ha;
}
void
fh_deleteheap(struct fibheap *h)
{
/*
* We could do this even faster by walking each binomial tree, but
* this is simpler to code.
*/
while (h->fh_min != NULL)
fhe_destroy(fh_extractminel(h));
fh_destroyheap(h);
}
/*
* Public Key Heap Functions
*/
struct fibheap_el *
fh_insertkey(struct fibheap *h, int key, void *data)
{
struct fibheap_el *x;
if ((x = fhe_newelem()) == NULL)
return NULL;
/* just insert on root list, and make sure it's not the new min */
x->fhe_data = data;
x->fhe_key = key;
fh_insertel(h, x);
return x;
}
int
fh_minkey(struct fibheap *h)
{
if (h->fh_min == NULL)
return INT_MIN;
return h->fh_min->fhe_key;
}
int
fh_replacekey(struct fibheap *h, struct fibheap_el *x, int key)
{
int ret;
ret = x->fhe_key;
(void)fh_replacekeydata(h, x, key, x->fhe_data);
return ret;
}
void *
fh_replacekeydata(struct fibheap *h, struct fibheap_el *x, int key, void *data)
{
void *odata;
int okey;
struct fibheap_el *y;
int r;
odata = x->fhe_data;
okey = x->fhe_key;
/*
* we can increase a key by deleting and reinserting, that
* requires O(lgn) time.
*/
if ((r = fh_comparedata(h, key, data, x)) > 0) {
/* XXX - bad code! */
abort();
fh_deleteel(h, x);
x->fhe_data = data;
x->fhe_key = key;
fh_insertel(h, x);
return odata;
}
x->fhe_data = data;
x->fhe_key = key;
/* because they are equal, we don't have to do anything */
if (r == 0)
return odata;
y = x->fhe_p;
if (h->fh_keys && okey == key)
return odata;
if (y != NULL && fh_compare(h, x, y) <= 0) {
fh_cut(h, x, y);
fh_cascading_cut(h, y);
}
/*
* the = is so that the call from fh_delete will delete the proper
* element.
*/
if (fh_compare(h, x, h->fh_min) <= 0)
h->fh_min = x;
return odata;
}
/*
* Public void * Heap Functions
*/
/*
* this will return these values:
* NULL failed for some reason
* ptr token to use for manipulation of data
*/
struct fibheap_el *
fh_insert(struct fibheap *h, void *data)
{
struct fibheap_el *x;
if ((x = fhe_newelem()) == NULL)
return NULL;
/* just insert on root list, and make sure it's not the new min */
x->fhe_data = data;
fh_insertel(h, x);
return x;
}
void *
fh_min(struct fibheap *h)
{
if (h->fh_min == NULL)
return NULL;
return h->fh_min->fhe_data;
}
void *
fh_extractmin(struct fibheap *h)
{
struct fibheap_el *z;
void *ret;
ret = NULL;
if (h->fh_min != NULL) {
z = fh_extractminel(h);
ret = z->fhe_data;
#ifndef NO_FREE
fhe_destroy(z);
#endif
}
return ret;
}
void *
fh_replacedata(struct fibheap *h, struct fibheap_el *x, void *data)
{
return fh_replacekeydata(h, x, x->fhe_key, data);
}
void *
fh_delete(struct fibheap *h, struct fibheap_el *x)
{
void *k;
k = x->fhe_data;
if (!h->fh_keys)
fh_replacedata(h, x, h->fh_neginf);
else
fh_replacekey(h, x, INT_MIN);
fh_extractmin(h);
return k;
}
/*
* Statistics Functions
*/
#ifdef FH_STATS
int
fh_maxn(struct fibheap *h)
{
return h->fh_maxn;
}
int
fh_ninserts(struct fibheap *h)
{
return h->fh_ninserts;
}
int
fh_nextracts(struct fibheap *h)
{
return h->fh_nextracts;
}
#endif
/*
* begin of private element fuctions
*/
static struct fibheap_el *
fh_extractminel(struct fibheap *h)
{
struct fibheap_el *ret;
struct fibheap_el *x, *y, *orig;
ret = h->fh_min;
orig = NULL;
/* put all the children on the root list */
/* for true consistancy, we should use fhe_remove */
for(x = ret->fhe_child; x != orig && x != NULL;) {
if (orig == NULL)
orig = x;
y = x->fhe_right;
x->fhe_p = NULL;
fh_insertrootlist(h, x);
x = y;
}
/* remove minimum from root list */
fh_removerootlist(h, ret);
h->fh_n--;
/* if we aren't empty, consolidate the heap */
if (h->fh_n == 0)
h->fh_min = NULL;
else {
h->fh_min = ret->fhe_right;
fh_consolidate(h);
}
#ifdef FH_STATS
h->fh_nextracts++;
#endif
return ret;
}
static void
fh_insertrootlist(struct fibheap *h, struct fibheap_el *x)
{
if (h->fh_root == NULL) {
h->fh_root = x;
x->fhe_left = x;
x->fhe_right = x;
return;
}
fhe_insertafter(h->fh_root, x);
}
static void
fh_removerootlist(struct fibheap *h, struct fibheap_el *x)
{
if (x->fhe_left == x)
h->fh_root = NULL;
else
h->fh_root = fhe_remove(x);
}
static void
fh_consolidate(struct fibheap *h)
{
struct fibheap_el **a;
struct fibheap_el *w;
struct fibheap_el *y;
struct fibheap_el *x;
int i;
int d;
int D;
fh_checkcons(h);
/* assign a the value of h->fh_cons so I don't have to rewrite code */
D = h->fh_Dl + 1;
a = h->fh_cons;
for (i = 0; i < D; i++)
a[i] = NULL;
while ((w = h->fh_root) != NULL) {
x = w;
fh_removerootlist(h, w);
d = x->fhe_degree;
/* XXX - assert that d < D */
while(a[d] != NULL) {
y = a[d];
if (fh_compare(h, x, y) > 0)
swap(struct fibheap_el *, x, y);
fh_heaplink(h, y, x);
a[d] = NULL;
d++;
}
a[d] = x;
}
h->fh_min = NULL;
for (i = 0; i < D; i++)
if (a[i] != NULL) {
fh_insertrootlist(h, a[i]);
if (h->fh_min == NULL || fh_compare(h, a[i],
h->fh_min) < 0)
h->fh_min = a[i];
}
}
static void
fh_heaplink(struct fibheap *h, struct fibheap_el *y, struct fibheap_el *x)
{
/* make y a child of x */
if (x->fhe_child == NULL)
x->fhe_child = y;
else
fhe_insertbefore(x->fhe_child, y);
y->fhe_p = x;
x->fhe_degree++;
y->fhe_mark = 0;
}
static void
fh_cut(struct fibheap *h, struct fibheap_el *x, struct fibheap_el *y)
{
fhe_remove(x);
y->fhe_degree--;
fh_insertrootlist(h, x);
x->fhe_p = NULL;
x->fhe_mark = 0;
}
static void
fh_cascading_cut(struct fibheap *h, struct fibheap_el *y)
{
struct fibheap_el *z;
while ((z = y->fhe_p) != NULL) {
if (y->fhe_mark == 0) {
y->fhe_mark = 1;
return;
} else {
fh_cut(h, y, z);
y = z;
}
}
}
/*
* begining of handling elements of fibheap
*/
static struct fibheap_el *
fhe_newelem()
{
struct fibheap_el *e;
if ((e = malloc(sizeof *e)) == NULL)
return NULL;
fhe_initelem(e);
return e;
}
static void
fhe_initelem(struct fibheap_el *e)
{
e->fhe_degree = 0;
e->fhe_mark = 0;
e->fhe_p = NULL;
e->fhe_child = NULL;
e->fhe_left = e;
e->fhe_right = e;
e->fhe_data = NULL;
}
static void
fhe_insertafter(struct fibheap_el *a, struct fibheap_el *b)
{
if (a == a->fhe_right) {
a->fhe_right = b;
a->fhe_left = b;
b->fhe_right = a;
b->fhe_left = a;
} else {
b->fhe_right = a->fhe_right;
a->fhe_right->fhe_left = b;
a->fhe_right = b;
b->fhe_left = a;
}
}
static inline void
fhe_insertbefore(struct fibheap_el *a, struct fibheap_el *b)
{
fhe_insertafter(a->fhe_left, b);
}
static struct fibheap_el *
fhe_remove(struct fibheap_el *x)
{
struct fibheap_el *ret;
if (x == x->fhe_left)
ret = NULL;
else
ret = x->fhe_left;
/* fix the parent pointer */
if (x->fhe_p != NULL && x->fhe_p->fhe_child == x)
x->fhe_p->fhe_child = ret;
x->fhe_right->fhe_left = x->fhe_left;
x->fhe_left->fhe_right = x->fhe_right;
/* clear out hanging pointers */
x->fhe_p = NULL;
x->fhe_left = x;
x->fhe_right = x;
return ret;
}
static void
fh_checkcons(struct fibheap *h)
{
int oDl;
/* make sure we have enough memory allocated to "reorganize" */
if (h->fh_Dl == -1 || h->fh_n > (1 << h->fh_Dl)) {
oDl = h->fh_Dl;
if ((h->fh_Dl = ceillog2(h->fh_n) + 1) < 8)
h->fh_Dl = 8;
if (oDl != h->fh_Dl)
h->fh_cons = (struct fibheap_el **)realloc(h->fh_cons,
sizeof *h->fh_cons * (h->fh_Dl + 1));
if (h->fh_cons == NULL)
abort();
}
}
static int
fh_compare(struct fibheap *h, struct fibheap_el *a, struct fibheap_el *b)
{
if (h->fh_keys) {
if (a->fhe_key < b->fhe_key)
return -1;
if (a->fhe_key == b->fhe_key)
return 0;
return 1;
} else
return h->fh_cmp_fnct(a->fhe_data, b->fhe_data);
}
static int
fh_comparedata(struct fibheap *h, int key, void *data, struct fibheap_el *b)
{
struct fibheap_el a;
a.fhe_key = key;
a.fhe_data = data;
return fh_compare(h, &a, b);
}
static void
fh_insertel(struct fibheap *h, struct fibheap_el *x)
{
fh_insertrootlist(h, x);
if (h->fh_min == NULL || (h->fh_keys ? x->fhe_key < h->fh_min->fhe_key
: h->fh_cmp_fnct(x->fhe_data, h->fh_min->fhe_data) < 0))
h->fh_min = x;
h->fh_n++;
#ifdef FH_STATS
if (h->fh_n > h->fh_maxn)
h->fh_maxn = h->fh_n;
h->fh_ninserts++;
#endif
}
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