/* --- Function: int HEAPinsert(Heap hp, const void *data) --- */
int HEAPinsert(Heap hp, const void *data)
{
void *tmp;
int currpos, parentpos;
/* Allocate storage for the new node */
if ((tmp = realloc(hp->tree, (HEAPsize(hp) + 1) * sizeof(void *))) == NULL)
return -1;
else
hp->tree = (void **)tmp;
/* Insert the node after the last node */
hp->tree[HEAPsize(hp)] = (void *)data;
/* Heapify the tree by pushing the contents of the new node upward */
currpos = HEAPsize(hp);
parentpos = HEAPparent(currpos);
while (currpos > 0 && hp->compare(hp->tree[parentpos], hp->tree[currpos]) < 0)
{
/* Swap the contents of the current node and its parent */
tmp = hp->tree[parentpos];
hp->tree[parentpos] = hp->tree[currpos];
hp->tree[currpos] = tmp;
/* Move up one level in the tree to continue heapifying */
currpos = parentpos;
parentpos = HEAPparent(currpos);
}
/* Adjust the size of the heap to account for the inserted node */
hp->size++;
return 0;
}
/* --- Function: void HEAPdestroy(Heap hp) --- */
void HEAPdestroy(Heap hp)
{
int i;
if (hp->destroy != NULL)
{
for (i = 0; i < HEAPsize(hp); i++)
hp->destroy(hp->tree[i]);
}
free(hp->tree);
free(hp);
}
/* --- Function: int PQUEUEsize(PQueue pq) --- */
int PQUEUEsize(PQueue pq)
{
return HEAPsize(pq);
}
/* --- Function: int HEAPextract(Heap hp, void **data) --- */
int HEAPextract(Heap hp, void **data)
{
void *save, *temp;
int currpos, leftpos, rightpos, tmppos;
/* Do not allow extraction from an empty heap */
if (HEAPsize(hp) == 0)
return -1;
/* Extract and return node data at the top of the heap */
*data = hp->tree[0];
/* Store/Backup data of the last noded of the heap */
save = hp->tree[HEAPsize(hp) - 1];
/* Adjust(=Shrink) the size of the heap */
if (HEAPsize(hp) - 1 > 0)
{
if ((temp = (void **)realloc(hp->tree, (HEAPsize(hp) - 1) * sizeof(void *))) == NULL)
return -1;
else
hp->tree = temp;
/* Adjust the size of the heap to account for the extracted node */
hp->size--;
}
else
{
/* Manage the heap when extracting the last node - and return from call */
free(hp->tree);
hp->tree = NULL;
hp->size = 0;
return 0;
}
/* Copy the (earlier saved), last node - to the top */
hp->tree[0] = save;
/* Heapify the tree by pushing the contents of the new top - downwards... */
currpos = 0;
/* leftpos = HEAPleft(currpos); */
/* rightpos = HEAPright(currpos); */
while (1)
{
/* Select the child to swap with the current node */
leftpos = HEAPleft(currpos);
rightpos = HEAPright(currpos);
if (leftpos < HEAPsize(hp) && hp->compare(hp->tree[leftpos], hp->tree[currpos]) > 0)
tmppos = leftpos;
else
tmppos = currpos;
if (rightpos < HEAPsize(hp) && hp->compare(hp->tree[rightpos], hp->tree[tmppos]) > 0)
tmppos = rightpos;
/* When tmppos is equal to currpos, the heap property has been restored */
if (tmppos == currpos)
{
/* Time to return to caller... */
break;
}
else
{
/* Swap the contents of the current node and the selected child */
temp = hp->tree[tmppos];
hp->tree[tmppos] = hp->tree[currpos];
hp->tree[currpos] = temp;
/* Move down one level in the tree to continue heapifying */
currpos = tmppos;
}
}
return 0;
}
