// Finds and removes replacement node for deletion (third case).
private IAvlNode RemoveReplacement(IAvlNode node, ref IAvlNode replacement)
{
IAvlNode newNode;
// If the bottom of the left tree has been found.
if (node.LeftChild == AvlNode.NullNode)
{
// The replacement node is the node found at this point.
replacement = node;
// Get the node's right child. This will be needed as we
// ascend back up the tree.
newNode = node.RightChild;
}
// Else the bottom of the left tree has not been found.
else
{
// Create new node and continue descending down the left tree.
newNode = new AvlNode(node.Data,
RemoveReplacement(node.LeftChild, ref replacement),
node.RightChild);
// If the node is out of balance.
if (!newNode.IsBalanced())
{
// Rebalance the node.
newNode = newNode.Balance();
}
}
// Postconditions.
Debug.Assert(newNode.IsBalanced());
return(newNode);
}