private IEnumerator <T> GetPostOrderEnumerator()
{
Stack <AvlNode <T> > stack = new Stack <AvlNode <T> >();
AvlNode <T> current = Root;
AvlNode <T> lastVisited = null;
while (current.IsNotNull())
{
for (; current.Left.IsNotNull(); current = current.Left)
{
stack.Push(current);
}
while (current.IsNotNull() && (current.Right.IsNull() || current.Right == lastVisited))
{
yield return(current.Item);
lastVisited = current;
if (stack.IsEmpty)
{
yield break;
}
current = stack.Pop();
}
stack.Push(current);
current = current.Right;
}
}
// T(n) = O(n); S(n) = O(h) (height)
private IEnumerator <T> GetInOrderEnumerator()
{
Stack <AvlNode <T> > stack = new Stack <AvlNode <T> >();
AvlNode <T> current = Root;
while (current.IsNotNull() || !stack.IsEmpty)
{
while (current.IsNotNull())
{
stack.Push(current);
current = current.Left;
}
if (!stack.IsEmpty)
{
current = stack.Pop();
yield return(current.Item);
current = current.Right;
}
}
}
protected AvlNode <T> FindMin(AvlNode <T> tree)
{
if (tree.IsNotNull())
{
while (tree.Left.IsNotNull())
{
tree = tree.Left;
}
}
return(tree);
}
protected AvlNode <T> FindMax(AvlNode <T> tree)
{
if (tree.IsNotNull())
{
while (tree.Right.IsNotNull())
{
tree = tree.Right;
}
}
return(tree);
}
private AvlNode <T> Find(AvlNode <T> node, T item)
{
AvlNode <T> current = node;
while (current.IsNotNull())
{
if (current.Item.CompareTo(item) == 0)
{
return(current); // Match
}
else if (current.Item.CompareTo(item) > 0)
{
current = current.Left;
}
else
{
current = current.Right;
}
}
return(null); // Not found.
}