private bool Search(SkipListElement anchor, int val)
{
var e = anchor;
while (e != null)
{
if (e.Value == val)
{
return(true);
}
if (e.Next == null || e.Next.Value > val)
{
break;
}
e = e.Next;
}
if (e.Down != null)
{
return(Search(e.Down, val));
}
return(false);
}
public void Insert(int val)
{
var height = GetRandomHeight();
var e = new SkipListElement {
Height = 0, Value = val
};
if (first.Next == null)
{
first.Next = e;
}
else
{
while (e.Height <= this.listHeight)
{
var upperElement = new SkipListElement
{
Height = e.Height + 1,
Value = e.Value,
Down = e
};
e = upperElement;
}
TraverseSkipList(first, e);
}
while (e.Height <= height)
{
var upperElement = new SkipListElement
{
Height = e.Height + 1,
Value = e.Value,
Down = e
};
e = upperElement;
}
// increase list height to element height if lower
int heightDiff = height - listHeight;
while (heightDiff > 0)
{
var newFirst = new SkipListElement {
Down = this.first, Next = e
};
this.first = newFirst;
e = e.Down;
heightDiff--;
}
this.listHeight = Math.Max(height, listHeight);
}
private void TraverseSkipList(SkipListElement anchor, SkipListElement val)
{
SkipListElement position = FindPosition(anchor, val.Value);
if (position.Down != null)
{
TraverseSkipList(position.Down, val.Down);
}
UpdateReferences(position, val);
}
private SkipListElement FindPosition(SkipListElement element, int val)
{
while (element != null)
{
if (element.Next != null && element.Next.Value < val)
{
element = element.Next;
}
else
{
return(element);
}
}
return(element);
}
public SkipList()
{
l0 = new SkipListElement();
first = l0;
}
private void UpdateReferences(SkipListElement o, SkipListElement next)
{
next.Next = o.Next;
o.Next = next;
}