public bool Delete(T value)
{
if (this.Root == null)
{
return(false);
}
if (this.Root.Value.CompareTo(value) == 0 && this.Root.IsLeaf)
{
this.Root = null;
return(true);
}
var nodeToRemove = this.Search(value);
if (nodeToRemove == null)
{
return(false);
}
this.Delete(nodeToRemove);
return(true);
}
public void Clear()
{
Root = null;
}
// Maximum of left subtree
public BinarySearchTreeNode <T> Predecessor(BinarySearchTreeNode <T> node)
{
return(Maximum(node.Left));
}
// Minimum of right subtree
public BinarySearchTreeNode <T> Successor(BinarySearchTreeNode <T> node)
{
return(Minimum(node.Right));
}
private void Delete(BinarySearchTreeNode <T> node)
{
// if node hasn't children then just remove this node
if (node.IsLeaf)
{
if (node.IsLeftChild)
{
node.Parent.Left = null;
}
else if (node.IsRightChild)
{
node.Parent.Right = null;
}
node.Parent = null;
return;
}
// if node has only 1 child then replace node by child
if (node.HasLeft ^ node.HasRight)
{
if (!node.HasParent)
{
if (!node.HasRight && node.HasLeft)
{
Root = node.Left;
}
else if (node.HasRight && !node.HasLeft)
{
Root = node.Right;
}
Root.Parent = null;
return;
}
if (node.HasLeft)
{
if (node.IsLeftChild)
{
node.Parent.Left = node.Left;
}
else
{
node.Parent.Right = node.Left;
}
node.Left.Parent = node.Parent;
}
else if (node.HasRight)
{
if (node.IsLeftChild)
{
node.Parent.Left = node.Right;
}
else
{
node.Parent.Right = node.Right;
}
node.Right.Parent = node.Parent;
}
return;
}
// if node has both childs
var successor = Successor(node);
node.Value = successor.Value;
this.Delete(successor);
}
