private bool DeleteInternal(T data, BinarySearchTreeNode <T> currentNode)
{
if (currentNode.Data.Equals(data))
{
// if there is no parent or children, then there's only 1 node in the BST, and we can simply delete it
if (currentNode.LeftChild == null && currentNode.RightChild == null && currentNode.Parent == null)
{
this._root = null;
}
if (currentNode.Parent == null)
{
if (currentNode.LeftChild != null)
{
this._root = currentNode.LeftChild;
currentNode.LeftChild.Parent = null;
if (currentNode.RightChild != null)
{
this.InsertInternal(currentNode.RightChild, currentNode.LeftChild);
}
}
else if (currentNode.RightChild != null)
{
this._root = currentNode.RightChild;
currentNode.RightChild.Parent = null;
}
return(true);
}
bool currentNodeIsLeftChild = currentNode.Parent.LeftChild == currentNode;
if (currentNode.LeftChild != null)
{
if (currentNodeIsLeftChild)
{
currentNode.Parent.LeftChild = currentNode.LeftChild;
}
else
{
currentNode.Parent.RightChild = currentNode.LeftChild;
}
currentNode.LeftChild.Parent = currentNode.Parent;
if (currentNode.RightChild != null)
{
this.InsertInternal(currentNode.RightChild, this._root);
}
}
else if (currentNode.RightChild != null)
{
if (currentNodeIsLeftChild)
{
currentNode.Parent.LeftChild = currentNode.RightChild;
}
else
{
currentNode.Parent.RightChild = currentNode.RightChild;
}
currentNode.RightChild.Parent = currentNode.Parent;
}
else
{
// this is a leaf node
if (currentNodeIsLeftChild)
{
currentNode.Parent.LeftChild = null;
}
else
{
currentNode.Parent.RightChild = null;
}
}
return(true);
}
else if (data.CompareTo(currentNode.Data) < 1)
{
if (currentNode.LeftChild != null)
{
return(this.DeleteInternal(data, currentNode.LeftChild));
}
return(false);
}
else
{
if (currentNode.RightChild != null)
{
return(this.DeleteInternal(data, currentNode.RightChild));
}
return(false);
}
}
public BinarySearchTree()
{
this._root = null;
}