private void Remove(T value, Node <T> currentNode)
{
if (currentNode == null)
{
return;
}
int compResult = value.CompareTo(currentNode.value);
if (compResult == 0)
{
bool isLeftChild = currentNode.parent.left != null && currentNode.Equals(currentNode.parent.left);
Node <T> newParentRef;
//if there's no right branch
if (currentNode.right == null)
{
//if it's a leaf node
if (currentNode.left == null)
{
newParentRef = null;
}
else
{
newParentRef = currentNode.left;
currentNode.left.parent = currentNode.parent;
}
}
else
{
Node <T> replacement = GetNextMinNode(currentNode.right);
//Reset old parent's link to replacement node
if (replacement.parent.left != null && replacement.parent.left.Equals(replacement))
{
replacement.parent.left = null;
}
else
{
replacement.parent.right = null;
}
newParentRef = replacement;
replacement.parent = currentNode.parent;
replacement.left = currentNode.left;
if (currentNode.left != null)
{
currentNode.left.parent = replacement;
}
if (replacement.right == null)
{
replacement.right = currentNode.right;
}
}
if (isLeftChild)
{
currentNode.parent.left = newParentRef;
}
else
{
currentNode.parent.right = newParentRef;
}
}
else if (compResult > 0)
{
Remove(value, currentNode.right);
}
else
{
Remove(value, currentNode.left);
}
}
public void DeleteNode(Node <T> NodeToDelete)
{
//No children -> Just Delete
if (NodeToDelete.HasNoChildren())
{
if (NodeToDelete.Equals(Root))
{
Root = null;
return;
}
Traverse((Node <T> node) =>
{
if (node.Left != null)
{
if (node.Left.Equals(NodeToDelete))
{
node.Left = null;
}
}
if (node.Right != null)
{
if (node.Right.Equals(NodeToDelete))
{
node.Right = null;
}
}
}, TraversalType.PostOrder);
return;
}
//Exactly one child -> Swap
if (NodeToDelete.HasOneChild())
{
if (NodeToDelete.Equals(Root))
{
Root = Root.Child();
return;
}
Traverse((Node <T> node) =>
{
if (node.Left != null)
{
if (node.Left.Equals(NodeToDelete))
{
node.Left = NodeToDelete.Child();
}
}
if (node.Right != null)
{
if (node.Right.Equals(NodeToDelete))
{
node.Right = NodeToDelete.Child();
}
}
}, TraversalType.PostOrder);
return;
}
//Find Minimum of Right sub-Tree, Copy Value, Delete Minimum
if (NodeToDelete.HasTwoChildren())
{
Node <T> SuccessorNode = MinValue(NodeToDelete.Right);
NodeToDelete.Value = SuccessorNode.Value;
DeleteNode(SuccessorNode);
return;
}
}