void SkipList<T>::skipListInsert(const T& key){
nodePtr curr[maxLevel], prev[maxLevel], newNode;
int lvl, i;
curr[maxLevel-1] = root[maxLevel-1];
prev[maxLevel-1] = 0;
for(lvl = maxLevel -1; lvl >= 0; lvl--){
while(curr[lvl] && curr[lvl]->key < key){
prev[lvl] = curr[lvl];
curr[lvl] = *(curr[lvl]->next + lvl);
}
if(curr[lvl] && curr[lvl]->key == key)
return;
if(lvl > 0)
if(prev[lvl] == 0){
curr[lvl-1] = root[lvl-1];
prev[lvl-1] = 0;
}
else{
curr[lvl-1] = *(prev[lvl]->next+ lvl -1);
prev[lvl-1] = prev[lvl];
}
}
lvl = chooseLevel();
newNode = new SkipListNode<T>;
newNode->next = new nodePtr[sizeof(nodePtr) * (lvl+1)];
newNode->key = key;
for(i = 0; i <= lvl; i++){
*(newNode->next + i) == curr[i];
if(prev[i] == 0)
root[i] = newNode;
else *(prev[i]->next + i) = newNode;
}
}
void SkipList<T>::insert(const T& info)
{ // does NOT permit duplicates
nodePtr curr[MAX_LEVELS], prev[MAX_LEVELS], newNode;
int lvl, i;
curr[maxLevel-1] = root[maxLevel-1];
prev[maxLevel-1] = NULL;
for (lvl = maxLevel - 1; lvl >= 0; lvl--)
{
while (curr[lvl] && curr[lvl]->info < info)
{ // go to the next at the same level
prev[lvl] = curr[lvl];
curr[lvl] = *(curr[lvl]->next + lvl);
} // while larger and nodes at this level
if (curr[lvl] && curr[lvl]->info == info) // don't include duplicates
return;
if (lvl > 0) // if not at bottom level
{
if (prev[lvl] == NULL) // if prev is root
{
curr[lvl - 1] = root[lvl - 1]; // lower curr starts at root
prev[lvl - 1] = NULL; // lower prev set to indicate at root
}
else // else prev is not root
{
curr[lvl - 1] = *(prev[lvl]->next + lvl - 1);
// lower curr starts at the next of the lower level of the prev
prev[lvl - 1] = prev[lvl];
// lower prev set to the prev of this level
}
}
} // for each lvl
lvl = chooseLevel(); // generate randomly level for newNode;
// newNode = new SkipListNode<T>; commented out by Sean
// newNode->next = new nodePtr[sizeof(nodePtr) * (lvl+1)]; commented out by Sean
// newNode->info = info; commented out by Sean
newNode = new SkipListNode<T>(info, new nodePtr[lvl + 1]); // line substituted by Sean
for (i = 0; i <= lvl; i++)
{ // initialize next fields of newNode and reset prev to newNode
*(newNode->next + i) = curr[i];
if (prev[i] == NULL) // prev is root
root[i] = newNode;
else // prev is not root
*(prev[i]->next + i) = newNode;
} // each level of the new node.
} // insert()