protected override void InsertNode(AVLTreeNode <KeyT> parentNode, AVLTreeNode <KeyT> newNode)
{
if (parentNode == null)
{
throw new ArgumentNullException(nameof(parentNode));
}
if (newNode == null)
{
throw new ArgumentNullException(nameof(newNode));
}
if (newNode.Key.CompareTo(parentNode.Key) < 0)
{
if (parentNode.LeftNode == null)
{
parentNode.LeftNode = newNode;
}
else
{
this.InsertNode(parentNode.LeftNode, newNode);
// verify if balancing is needed {1}
if ((this.NodeHeight(parentNode.LeftNode) - this.NodeHeight(parentNode.RightNode)) > 1)
{
if (newNode.Key.CompareTo(parentNode.LeftNode.Key) < 0)
{
parentNode.LeftNode = this.RotationLL(parentNode);
}
else
{
parentNode.LeftNode = this.RotationLR(parentNode);
}
}
}
}
else
{
if (parentNode.RightNode == null)
{
parentNode.RightNode = newNode;
}
else
{
this.InsertNode(parentNode.RightNode, newNode);
// verify if balancing is needed {2}
if ((this.NodeHeight(parentNode.RightNode) - this.NodeHeight(parentNode.LeftNode)) > 1)
{
if (newNode.Key.CompareTo(parentNode.RightNode.Key) > 0)
{
parentNode.RightNode = this.RotationRR(parentNode);
}
else
{
parentNode.RightNode = this.RotationRL(parentNode);
}
}
}
}
}
protected AVLTreeNode <KeyT> RotationLR(AVLTreeNode <KeyT> node)
{
node.LeftNode = this.RotationRR(node.LeftNode);
return(this.RotationLL(node));
}
protected int NodeHeight(AVLTreeNode <KeyT> node)
{
return((node == null) ? -1 : Math.Max(NodeHeight(node.LeftNode), NodeHeight(node.RightNode)) + 1);
}