protected override void Remove(BinarySearchTreeNode <T> node)
{
if (node.HasRight && node.HasLeft)
{
var leftHeight = node.Left?.Height ?? 0;
var rightHeight = node.Right?.Height ?? 0;
var nodeToReplace = leftHeight > rightHeight
? this.GetPredecessor(node.Content)
: this.GetSuccessor(node.Content);
node.Content = nodeToReplace.Content;
node = nodeToReplace;
}
// has 1 or 0 child
var redBlackNode = node as RedBlackTreeNode <T>;
// if red and has no more than 1 child - it hasn't child
if (redBlackNode.IsRed)
{
this.RemoveLeaf(node);
return;
}
// node is black
var child = (node.HasLeft
? node.Left
: node.Right) as RedBlackTreeNode <T>;
// if black node has only 1 red child - copy content and remove child
// (red child cannot contain any nodes)
if (child != null && child.IsRed)
{
node.Content = child.Content;
this.RemoveLeaf(child);
return;
}
// node is black and no childs (black node cannot has just 1 black child)
this.UpdateColorOnRemove(redBlackNode);
this.RemoveLeaf(node);
}
protected override void Remove(BinarySearchTreeNode <T> node)
{
if (node.IsTerminate)
{
var parentNode = node.Parent as AVLTreeNode <T>;
this.RemoveLeaf(node);
this.RebalanceIn(parentNode as AVLTreeNode <T>);
}
else
{
var leftHeight = node.Left?.Height ?? -1;
var rightHeight = node.Right?.Height ?? -1;
var nodeToReplace = leftHeight > rightHeight
? this.GetPredecessor(node.Content)
: this.GetSuccessor(node.Content);
node.Content = nodeToReplace.Content;
this.Remove(nodeToReplace);
}
}
/// <summary>
/// Verifying AVL tree node
/// </summary>
/// <param name="node">Tree node</param>
/// <param name="min">Tree min node</param>
/// <param name="max">Tree max node</param>
/// <returns>True if AVL tree node is valid</returns>
protected override bool VerifyIn(BinarySearchTreeNode <T> node, BinarySearchTreeNode <T> min = null, BinarySearchTreeNode <T> max = null)
{
var avlNode = node as AVLTreeNode <T>;
return(avlNode.CalculatedHeight == avlNode.Height &&
Math.Abs(avlNode.BalanceFactor) < 2 &&
base.VerifyIn(node, min, max));
}
/// <summary>
/// Verifying RB tree node
/// </summary>
/// <param name="node">Tree node</param>
/// <param name="min">Tree min node</param>
/// <param name="max">Tree max node</param>
/// <returns>True if RB tree node is valid</returns>
protected override bool VerifyIn(BinarySearchTreeNode <T> node, BinarySearchTreeNode <T> min = null, BinarySearchTreeNode <T> max = null)
{
var redBlackNode = node as RedBlackTreeNode <T>;
var left = node.Left as RedBlackTreeNode <T>;
var right = node.Right as RedBlackTreeNode <T>;
var root = this.Root as RedBlackTreeNode <T>;
var isColorMatching = redBlackNode.IsRed
? ((!node.HasLeft || left.IsBlack) && (!node.HasRight || right.IsBlack))
: true;
return(root.IsBlack &&
isColorMatching &&
(left?.BlackHeight ?? 1) == (right?.BlackHeight ?? 1) &&
base.VerifyIn(node, min, max));
}
