static void fibheap_cascading_cut(fibheap_t *fib, fibnode_t *node)
{
fibnode_t *parent;
while ((parent = node->parent) != NULL) {
if (node->mark == 0) {
node->mark = 1;
return;
}
fibheap_cut(fib, node, parent);
node = parent;
}
}
static int __fibheap_decrease_key(fibheap_t *fib, fibnode_t *node, long key)
{
fibnode_t *parent = node->parent;
node->key = key;
if (parent && node->key <= parent->key) {
fibheap_cut(fib, node, parent);
fibheap_cascading_cut(fib, parent);
}
if (node->key <= fib->min->key)
fib->min = node;
return 0;
}
static void
fibheap_cascading_cut (fibheap_t heap, fibnode_t y)
{
fibnode_t z;
while ((z = y->parent) != NULL)
{
if (y->mark == 0)
{
y->mark = 1;
return;
}
else
{
fibheap_cut (heap, y, z);
y = z;
}
}
}
/* Replace both the KEY and the DATA associated with NODE. */
void *
fibheap_replace_key_data (fibheap_t heap, fibnode_t node,
fibheapkey_t key, void *data)
{
void *odata;
fibheapkey_t okey;
fibnode_t y;
/* If we wanted to, we could actually do a real increase by redeleting and
inserting. However, this would require O (log n) time. So just bail out
for now. */
if (fibheap_comp_data (heap, key, data, node) > 0) {
fprintf( stderr, "Unhandled case of fibheap key increase: bailing\n");
return NULL;
}
odata = node->data;
okey = node->key;
node->data = data;
node->key = key;
y = node->parent;
if (okey == key)
return odata;
/* These two compares are specifically <= 0 to make sure that in the case
of equality, a node we replaced the data on, becomes the new min. This
is needed so that delete's call to extractmin gets the right node. */
if (y != NULL && fibheap_compare (heap, node, y) <= 0)
{
fibheap_cut (heap, node, y);
fibheap_cascading_cut (heap, y);
}
if (fibheap_compare (heap, node, heap->min) <= 0)
heap->min = node;
return odata;
}