public AVLTreeNode(TNode value, AVLTreeNode <TNode> parent, AVLTree <TNode> tree)
{
Value = value;
Parent = parent;
_tree = tree;
}
/// <summary>
/// Removes the first occurrence of the specified value from the tree.
/// </summary>
/// <param name="value">The value to remove.</param>
/// <returns>True if the value was removed; false otherwise.</returns>
public bool Remove(T value) // O(log n)
{
AVLTreeNode <T> current;
current = Find(value);
if (current == null)
{
return(false);
}
AVLTreeNode <T> treeToBalance = current.Parent;
Count--;
//Case 1: If current has no right child, then current's left replaces current.
if (current.Right == null)
{
if (current.Parent == null)
{
Head = current.Left;
if (Head != null)
{
Head.Parent = null;
}
}
else
{
int result = current.Parent.CompareTo(current.Value);
if (result > 0)
{
// If the parent value is greater than the current value,
// make the current left child a left child of parent.
current.Parent.Left = current.Left;
}
else if (result < 0)
{
// If the parent value is less than the current value,
// make the current left child a right child of the parent.
current.Parent.Right = current.Left;
}
}
}
// Case 2: If current's right child has no left child, then current's right child replaces current.
else if (current.Right.Left == null)
{
current.Right.Left = current.Left;
if (current.Parent == null)
{
Head = current.Right;
if (Head != null)
{
Head.Parent = null;
}
}
else
{
int result = current.Parent.CompareTo(current.Value);
if (result > 0)
{
// If the parent value is greater than the current value,
// make the current the right child a left child of parent.
current.Parent.Left = current.Right;
}
}
}
// Case 3: If current's right child has a left child, replace current with
// current's right child's leftmost child.
else
{
// Find the right's leftmost child.
AVLTreeNode <T> leftmost = current.Right.Left;
while (leftmost.Left != null)
{
leftmost = leftmost.Left;
}
// The parent's left subtree becomes the leftmost's right subtree.
leftmost.Parent.Left = leftmost.Right;
//Asign leftmost's left and right to current's left and right children.
leftmost.Left = current.Left;
leftmost.Right = current.Right;
if (current.Parent == null)
{
Head = leftmost;
if (Head != null)
{
Head.Parent = null;
}
}
else
{
int result = current.Parent.CompareTo(current.Value);
if (result > 0)
{
// If the parent value is greater than the current value,
// make leftmost the parent's left child.
current.Parent.Left = leftmost;
}
else if (result < 0)
{
// If the parent value is less than the current value,
// make the leftmost parent's right child.
current.Parent.Right = leftmost;
}
}
}
if (treeToBalance != null)
{
treeToBalance.Balance();
}
else
{
if (Head != null)
{
Head.Balance();
}
}
return(true);
}
public void Clear() // O(1)
{
Head = null;
Count = 0;
}
