private INode <T> Remove(INode <T> node, T item, bool[] result)
{
if (node == null)
{
return(node);
}
else if (item.CompareTo(node.Item) < 0)
{
node.Left = Remove(node.Left, item, result);
}
else if (item.CompareTo(node.Item) > 0)
{
node.Right = Remove(node.Right, item, result);
}
else
{
result[0] = true;
if (node.Left == null && node.Right == null)
{
return(null);
}
else if (node.Left == null)
{
node = node.Right;
}
else if (node.Right == null)
{
node = node.Left;
}
else
{
INode <T> succ = FindSuccessor(node);
node.Item = succ.Item;
node.Right = Remove(node.Right, succ.Item, result);
}
}
AvlNode <T> avlNode = (AvlNode <T>)node;
AdjustHeight(avlNode);
int balance = GetBalance(avlNode);
return(CheckCasesRemove(balance, avlNode));
}
/// <summary>
/// Internal method to insert into a subtree.
/// </summary>
/// <param name="x">The item to insert.</param>
/// <param name="subTree">The node that roots the subtree. </param>
/// <returns></returns>
private AvlNode Insert(T x, AvlNode subTree)
{
if (subTree == null)
{
return(new AvlNode(x, null, null));
}
int compareResult = Compare(x, subTree.Element);
if (compareResult < 0)
{
subTree.Left = Insert(x, subTree.Left);
}
else if (compareResult > 0)
{
subTree.Right = Insert(x, subTree.Right);
}
else
{
/* Duplicate; Do nothing. */
}
return(Balance(subTree));
}
private int GetBalance(AvlNode <T> node)
{
return(GetHeight(node.AvlLeft) - GetHeight(node.AvlRight));
}
private void AdjustHeight(AvlNode <T> node)
{
node.Height = System.Math.Max(GetHeight(node.AvlLeft), GetHeight(node.AvlRight)) + 1;
}
/// <summary>
/// Return the height of the node, or -1 if null.
/// </summary>
/// <param name="node">The node that we are checking. </param>
/// <returns>The height of the node.</returns>
private int Height(AvlNode node)
{
return((node == null) ? -1 : node.Height);
}
public AvlNode(T element, AvlNode left, AvlNode right)
{
_element = element;
_left = left;
_right = right;
}
/// <summary>
/// Double rotate tree node. First right child with its left child; then node k3 with new right child.
/// For AVL trees, this is a double rotation for case 4. Update heights, the return new root.
/// </summary>
/// <param name="k2">The node that roots subtree that will be rotated.</param>
/// <returns>The node that roots the new subtree.</returns>
private AvlNode DoubleWithRightChild(AvlNode k3)
{
k3.Right = RotateWithLeftChild(k3.Right);
return(RotateWithRightChild(k3));
}
public AvlTree()
{
_root = null;
}