public bool Delete(T key)
{
var node = root;
while (node != null)
{
if (key.CompareTo(node.Key) < 0)
{
node = node.LeftChild;
}
else if (key.CompareTo(node.Key) > 0)
{
node = node.RightChild;
}
else
{
var left = node.LeftChild;
var right = node.RightChild;
if (left == null)
{
if (right == null)
{
if (node == root)
{
root = null;
}
else
{
var parent = node.Parent;
if (parent.LeftChild == node)
{
parent.LeftChild = null;
DeleteBalance(parent, -1);
}
else
{
parent.RightChild = null;
DeleteBalance(parent, 1);
}
}
}
else
{
Transplant(node, right);
DeleteBalance(node, 0);
}
}
else if (right == null)
{
Transplant(node, left);
DeleteBalance(node, 0);
}
else
{
var successor = right;
if (successor.LeftChild == null)
{
var parent = node.Parent;
successor.Parent = parent;
successor.LeftChild = left;
successor.Balance = node.Balance;
if (left != null)
{
left.Parent = successor;
}
if (node == root)
{
root = successor;
}
else
{
if (parent.LeftChild == node)
{
parent.LeftChild = successor;
}
else
{
parent.RightChild = successor;
}
}
DeleteBalance(successor, 1);
}
else
{
while (successor.LeftChild != null)
{
successor = successor.LeftChild;
}
var parent = node.Parent;
var successorParent = successor.Parent;
var successorRight = successor.RightChild;
if (successorParent.LeftChild == successor)
{
successorParent.LeftChild = successorRight;
}
else
{
successorParent.RightChild = successorRight;
}
if (successorRight != null)
{
successorRight.Parent = successorParent;
}
successor.Parent = parent;
successor.LeftChild = left;
successor.Balance = node.Balance;
successor.RightChild = right;
right.Parent = successor;
if (left != null)
{
left.Parent = successor;
}
if (node == root)
{
root = successor;
}
else
{
if (parent.LeftChild == node)
{
parent.LeftChild = successor;
}
else
{
parent.RightChild = successor;
}
}
DeleteBalance(successorParent, -1);
}
}
return(true);
}
}
return(false);
}