/// <summary>
/// Deletes the given value from the tree at the given root according to the BinarySearchTree algorithm and then
/// rebalances the tree.
/// </summary>
/// <param name="root">The root node of the tree</param>
/// <param name="value">The value to delete</param>
/// <returns>The new root of the tree as it may have changed</returns>
private AVLNode <T> Delete(AVLNode <T> root, T value)
{
int compareResults = root.Value.CompareTo(value);
if (compareResults > 0)
{
if (root.Left != null)
{
root.ResetHeight();
root.Left = Delete(root.Left, value);
}
else
{
throw new ValueNotFoundException();
}
}
else if (compareResults < 0)
{
if (root.Right != null)
{
root.ResetHeight();
root.Right = Delete(root.Right, value);
}
else
{
throw new ValueNotFoundException();
}
}
else
{
if (root.Left == null && root.Right == null)
{
--this.Count;
root = null;
}
else if (root.Right == null)
{
--this.Count;
root.Value = root.Left.Value;
root.Right = root.Left.Right;
root.Left = root.Left.Left;
root.ResetHeight();
}
else if (root.Left == null)
{
--this.Count;
root.Value = root.Right.Value;
root.Left = root.Right.Left;
root.Right = root.Right.Right;
root.ResetHeight();
}
else
{
AVLNode <T> predecessor = root.InOrderPredecessor;
root.Value = predecessor.Value;
root.Left = Delete(root.Left, predecessor.Value);
root.ResetHeight();
}
}
if (root != null)
{
root = RebalanceNode(root);
}
return(root);
}
private int GetChildNodeHeight(AVLNode <T> node)
{
return((node == null) ? -1 : node.Height);
}
