public void Add(T item)
{
if (head._right == null)
{
var newNode = new Skiplist <T> .Node <T>(item);
head._right = newNode;
newNode._left = head;
newNode._right = tail;
tail._left = newNode;
}
else
{
var newNode = AddNodeToBottomLevel(item);
int curHeight = 1;
while (WeakRandom.XorShift128(2) % 4 == 0)
{
curHeight++;
if (curHeight > maxHeight) //need to add a new head/tail level
{
AddLevel();
}
AddUpperNode(item, newNode);
}
}
}
private Node <T> AddNodeToBottomLevel(T item)
{
var bookmarkNode = this.FindEntry(item);
var newNode = new Skiplist <T> .Node <T>(item)
{
_right = bookmarkNode._right,
_left = bookmarkNode
};
bookmarkNode._right = newNode;
newNode._right._left = newNode;
return(newNode);
}
private void AddLevel()
{
var newHead = new Skiplist <T> .Node <T>();
var newTail = new Skiplist <T> .Node <T>();
head._up = newHead;
tail._up = newTail;
newHead._right = newTail;
newTail._left = newHead;
newHead._down = head;
newTail._down = tail;
head = newHead;
tail = newTail;
maxHeight++;
}