/* Add a new element to the skip list:
param: slst -- pointer to the skip list
param: e -- element to be added
pre: slst is not null
post: the new element is added to the lowest list and randomly to higher-level lists */
void addSkipList(struct skipList *slst, TYPE e)
{
/* Check if slst is null */
assert(slst);
struct skipLink *downLink, *newLink;
downLink = skipLinkAdd(slideRightSkipList(slst->topSentinel,e),e);
/* FIX ME*/
while(downLink)
{
/* Create new express lane with new head and new link */
newLink = newSkipLink(e, 0, downLink);
struct skipLink* newHead = newSkipLink(0, newLink, slst->topSentinel);
/* Update the new skipList top sentinel to point to new list */
slst->topSentinel = newHead;
/* If need to make new list, update downLink, else set to null */
if(flipSkipLink())
downLink = newLink;
else
downLink = 0;
}
/* Increase size */
slst->size++;
}
/* Remove an element from the skip list:
param: slst -- pointer to the skip list
param: e -- element to be removed
pre: slst is not null
post: the new element is removed from all internal sorted lists */
void removeSkipList(struct skipList *slst, TYPE e)
{
/* FIX ME*/
/* Check if slst is null */
assert(slst);
/* Only remove elements if skip list is not empty */
if(sizeSkipList(slst) > 0)
{
int foundLink = 0;
struct skipLink* curr = slst->topSentinel;
/* Slide right to find link before link with value e */
while(1)
{
/* Slide right to find link before link with value e*/
curr = slideRightSkipList(curr, e);
/* If next link value is e, free it and fix link connections */
if(curr->next && EQ(curr->next->value, e))
{
struct skipLink* tmp = curr->next;
curr->next = curr->next->next;
free(tmp);
foundLink = 1;
}
/* Exit loop is on bottom list, down link is null */
if(curr->down == 0)
break;
/* Set curr to down link */
curr = curr->down;
}
if(foundLink)
{
slst->size--;
/* Remove all empty lists */
struct skipLink* head = slst->topSentinel;
while(head->down)
{
if(head->next == 0)
{
struct skipLink* downHead = head->down;
free(head);
slst->topSentinel = downHead;
head = downHead;
}
else
break;
}
}
}
}
/* Checks if an element is in the skip list:
param: slst -- pointer to the skip list
param: e --
element to be checked
pre: slst is not null
post: returns true or false */
int containsSkipList(struct skipList *slst, TYPE e)
{
/* FIX ME*/
/* Check if slst is null */
assert(slst);
/* Loop through list if its not empty */
if(sizeSkipList(slst) > 0)
{
/* Get the link before value e and compare */
struct skipLink* curr = slst->topSentinel;
while(1)
{
curr = slideRightSkipList(curr, e);
/* Return true (1) if value e is found */
if(curr->next && EQ(curr->next->value, e))
return 1;
else if(curr->down == 0)
break;
curr = curr->down;
}
}
/* Return false (0) if value e is not found */
return 0;
}
/* Checks if an element is in the skip list:
param: slst -- pointer to the skip list
param: e -- element to be checked
pre: slst is not null
post: returns true or false */
int containsSkipList(struct skipList *slst, TYPE e)
{
struct skipLink *current = slst->topSentinel;
while (current){
current = slideRightSkipList(current, e);
if((current->next !=0) && EQ(current->next->value, e)) return 1;
current = current->down;
}
return 0;
}
/* Add a new element to the skip list:
param: slst -- pointer to the skip list
param: e -- element to be added
pre: slst is not null
post: the new element is added to the lowest list and randomly to higher-level lists */
void addSkipList(struct skipList *slst, TYPE e)
{
struct skipLink *downLink, *newLink;
downLink = skipLinkAdd(slideRightSkipList(slst->topSentinel, e), e);
if (downLink != 0 && flipSkipLink()) {
struct skipLink* newTopSentinel = (struct skipLink *) malloc(sizeof(struct skipLink));
newLink = newSkipLink(e, 0, downLink);
newTopSentinel->next = newLink;
newTopSentinel->down = slst->topSentinel;
slst->topSentinel = newTopSentinel;
}
slst->size++;
}
/* Remove an element from the skip list:
param: slst -- pointer to the skip list
param: e -- element to be removed
pre: slst is not null
post: the new element is removed from all internal sorted lists */
void removeSkipList(struct skipList *slst, TYPE e)
{
/* FIX ME*/
struct skipLink *current = slst->topSentinel;
while(current != NULL){
current = slideRightSkipList(current, e);
if(current->next->value == e)
current->next = current->next->next; /*POSSIBLE ERROR!!!!!!!!!!!!!!!*/
if(current->down == NULL)
slst->size--;
}
}
/* Remove an element from the skip list:
param: slst -- pointer to the skip list
param: e -- element to be removed
pre: slst is not null
post: the new element is removed from all internal sorted lists */
void removeSkipList(struct skipList *slst, TYPE e)
{
struct skipLink *current, *temp;
current = slst->topSentinel;
while (current){
current = slideRightSkipList(current, e);
if((current->next != 0) && EQ(current->next->value, e)){
temp = current->next;
current->next = current->next->next;
free(temp);
if(current->down == NULL) slst->size--;
}
current = current->down;
}
}
/* Add a new skip link recursively
param: current -- pointer to a place in the list where the new element should be inserted
param: e -- the value to create a link for
pre: current is not NULL
post: a link to store the value */
struct skipLink* skipLinkAdd(struct skipLink * current, TYPE e) {
struct skipLink *newLink, *downLink;
newLink = 0;
if (current->down == 0) {
newLink = newSkipLink(e, current->next, 0);
current->next = newLink;
}
else {
downLink = skipLinkAdd(slideRightSkipList(current->down, e), e);
if (downLink != 0 && flipSkipLink()) {
newLink = newSkipLink(e, current->next, downLink);
current->next = newLink;
}
}
return newLink;
}
/* Checks if an element is in the skip list:
param: slst -- pointer to the skip list
param: e -- element to be checked
pre: slst is not null
post: returns true or false */
int containsSkipList(struct skipList *slst, TYPE e)
{
/* FIX ME*/
assert(slst != 0);
struct skipLink *current = slst->topSentinel;
while(current!=NULL){
current = slideRightSkipList(current, e);
if(current->next->value == e)
return 1; /*The element is in the list*/
else
current = current->down;
}
return 0; /*The element is not in the list*/
}
/* Add a new element to the skip list:
param: slst -- pointer to the skip list
param: e -- element to be added
pre: slst is not null
post: the new element is added to the lowest list and randomly to higher-level lists */
void addSkipList(struct skipList *slst, TYPE e)
{
int r = rand()%5;
struct skipLink *downLink, *topLink, *temp;
topLink = (struct skipLink *)malloc(sizeof(struct skipLink));
downLink = skipLinkAdd(slideRightSkipList(slst->topSentinel,e),e);
if(r==1){
temp = slst->topSentinel;
/* FIX ME*/
slst->size++;
assert(topLink!=0);
slst->topSentinel = topLink;
topLink->next = downLink;
topLink->down = temp;
}
}
