/// <summary>
/// Balances a subtree to comply with AVL property.
/// </summary>
/// <param name="node">The root node of the subtree.</param>0
protected void Balance(AvlNode node)
{
while (node != null)
{
node.Balance = AvlNode.GetBalance(node);
Int32 newHeight = AvlNode.GetHeight(node);
if (newHeight == node.Height)
{
return;
}
node.Height = newHeight;
switch (node.Balance)
{
case -2:
switch ((node.LeftChild as AvlNode).Balance)
{
case 0: // --,=
case -1: // --,-
node = RotateRight(node) as AvlNode;
(node.RightChild as AvlNode).Height = AvlNode.GetHeight(node.RightChild);
(node.RightChild as AvlNode).Balance = AvlNode.GetBalance(node.RightChild);
node.Height = AvlNode.GetHeight(node);
node.Balance = AvlNode.GetBalance(node);
break;
case 1: // --,+
RotateLeft(node.LeftChild);
node = RotateRight(node) as AvlNode;
(node.LeftChild as AvlNode).Height = AvlNode.GetHeight(node.LeftChild);
(node.LeftChild as AvlNode).Balance = AvlNode.GetBalance(node.LeftChild);
(node.RightChild as AvlNode).Height = AvlNode.GetHeight(node.RightChild);
(node.RightChild as AvlNode).Balance = AvlNode.GetBalance(node.RightChild);
node.Height = AvlNode.GetHeight(node);
node.Balance = AvlNode.GetBalance(node);
break;
}
break;
case 2:
switch ((node.RightChild as AvlNode).Balance)
{
case 0: // ++,=
case 1: // ++,+
node = RotateLeft(node) as AvlNode;
(node.LeftChild as AvlNode).Height = AvlNode.GetHeight(node.LeftChild);
(node.LeftChild as AvlNode).Balance = AvlNode.GetBalance(node.LeftChild);
node.Height = AvlNode.GetHeight(node);
node.Balance = AvlNode.GetBalance(node);
break;
case -1: // ++,-
RotateRight(node.RightChild);
node = RotateLeft(node) as AvlNode;
(node.LeftChild as AvlNode).Height = AvlNode.GetHeight(node.LeftChild);
(node.LeftChild as AvlNode).Balance = AvlNode.GetBalance(node.LeftChild);
(node.RightChild as AvlNode).Height = AvlNode.GetHeight(node.RightChild);
(node.RightChild as AvlNode).Balance = AvlNode.GetBalance(node.RightChild);
node.Height = AvlNode.GetHeight(node);
node.Balance = AvlNode.GetBalance(node);
break;
}
break;
}
node = node.Parent as AvlNode;
}
}
private int Height(AvlNode node)
{
return(node == null ? -1 : node.GetHeight());
}
