private void RightRotate(RBTNode node)
{
var leftNode = node.Left;
leftNode.Right = node.Right;
if (leftNode.Right != NIL)
{
leftNode.Right.Parent = node;
}
leftNode.Parent = node.Parent;
if (node.Parent == NIL)
{
Root = leftNode;
}
else if (node == node.Parent.Right)
{
node.Parent.Right = leftNode;
}
else
{
node.Parent.Left = leftNode;
}
leftNode.Right = node;
node.Parent = leftNode;
}
private void LeftRotate(RBTNode node)
{
var rightNode = node.Right;
rightNode.Right = node.Left;
if (rightNode.Left != NIL)
{
rightNode.Left.Parent = node;
}
rightNode.Parent = node.Parent;
if (node.Parent == NIL)
{
Root = rightNode;
}
else if (node == node.Parent.Left)
{
node.Parent.Left = rightNode;
}
else
{
node.Parent.Right = rightNode;
}
rightNode.Left = node;
node.Parent = rightNode;
}
public RBTNode Maximum(RBTNode node)
{
while (node.Right != NIL)
{
node = node.Right;
}
return(node);
}
public RBTNode Minimum(RBTNode node)
{
while (node.Left != NIL)
{
node = node.Left;
}
return(node);
}
private void InsertFixup(RBTNode node)
{
while (node.Parent.Color.IsRed())
{
if (node.Parent == node.Parent.Parent.Left)
{
var uncleNode = node.Parent.Parent.Right;
if (uncleNode.Color.IsRed())
{
node.Parent.SetBlack();
uncleNode.SetBlack();
node.Parent.Parent.SetRed();
node = node.Parent.Parent;
}
else
{
if (node == node.Parent.Right)
{
node = node.Parent;
LeftRotate(node);
}
node.Parent.SetBlack();
node.Parent.Parent.SetRed();
RightRotate(node.Parent.Parent);
}
}
else
{
var uncleNode = node.Parent.Parent.Left;
if (uncleNode.Color.IsRed())
{
node.Parent.SetBlack();
uncleNode.SetBlack();
node.Parent.Parent.SetRed();
node = node.Parent.Parent;
}
else
{
if (node == node.Parent.Left)
{
node = node.Parent;
RightRotate(node);
}
node.Parent.SetBlack();
node.Parent.Parent.SetRed();
LeftRotate(node.Parent.Parent);
}
}
Root.SetBlack();
}
}
public RBTNode Search(RBTNode node, int key)
{
while (node != NIL && key != node.Key)
{
if (key < node.Key)
{
node = node.Left;
}
else
{
node = node.Right;
}
}
return(node);
}
public RBTNode Predeccessor(RBTNode node)
{
if (node.Left != NIL)
{
return(Maximum(node.Left));
}
var prevnode = node.Parent;
while (prevnode != NIL && node != prevnode.Left)
{
node = prevnode;
prevnode = prevnode.Parent;
}
return(prevnode);
}
public RBTNode Successor(RBTNode node)
{
if (node.Right != NIL)
{
return(Minimum(node.Right));
}
var prevnode = node.Parent;
while (prevnode != NIL && node != prevnode.Right)
{
node = prevnode;
prevnode = prevnode.Parent;
}
return(prevnode);
}
private void Transplant(RBTNode nodeToReplace, RBTNode replacedNode)
{
if (nodeToReplace.Parent == NIL)
{
Root = replacedNode;
}
else if (nodeToReplace == nodeToReplace.Parent.Left)
{
nodeToReplace.Parent.Left = replacedNode;
}
else
{
nodeToReplace.Parent.Right = replacedNode;
}
replacedNode.Parent = nodeToReplace.Parent;
}
public void Insert(int key)
{
var nodeToInsert = new RBTNode(key);
RBTNode prevnode = NIL;
var node = Root;
while (node != NIL)
{
prevnode = node;
if (nodeToInsert.Key < node.Key)
{
node = node.Left;
}
else
{
node = node.Right;
}
}
nodeToInsert.Parent = prevnode;
if (prevnode == NIL)
{
Root = nodeToInsert;
}
else if (nodeToInsert.Key < prevnode.Key)
{
prevnode.Left = nodeToInsert;
}
else
{
prevnode.Right = nodeToInsert;
}
nodeToInsert.Left = NIL;
nodeToInsert.Right = NIL;
InsertFixup(nodeToInsert);
}
private void DeleteFixup(RBTNode badNode)
{
RBTNode brotherNode;
while (badNode != Root && badNode.Color.IsBlack())
{
if (badNode == badNode.Parent.Left)
{
brotherNode = badNode.Parent.Right;
if (brotherNode.Color.IsRed())
{
brotherNode.SetBlack();
badNode.Parent.SetRed();
LeftRotate(badNode.Parent);
brotherNode = badNode.Parent.Right;
}
if (brotherNode.Left.Color.IsBlack() && brotherNode.Right.Color.IsBlack())
{
brotherNode.SetRed();
badNode = badNode.Parent;
}
else
{
if (brotherNode.Right.Color.IsBlack())
{
brotherNode.Left.SetBlack();
brotherNode.SetRed();
RightRotate(brotherNode);
brotherNode = badNode.Parent.Right;
}
brotherNode.Color = badNode.Parent.Color;
badNode.Parent.SetBlack();
LeftRotate(badNode.Parent);
badNode = Root;
}
}
else
{
brotherNode = badNode.Parent.Left;
if (brotherNode.Color.IsRed())
{
brotherNode.SetBlack();
badNode.Parent.SetRed();
RightRotate(badNode.Parent);
brotherNode = badNode.Parent.Left;
}
if (brotherNode.Left.Color.IsBlack() && brotherNode.Right.Color.IsBlack())
{
brotherNode.SetRed();
badNode = badNode.Parent;
}
else
{
if (brotherNode.Right.Color.IsBlack())
{
brotherNode.Right.SetBlack();
brotherNode.SetRed();
LeftRotate(brotherNode);
brotherNode = badNode.Parent.Left;
}
brotherNode.Color = badNode.Parent.Color;
badNode.Parent.SetBlack();
RightRotate(badNode.Parent);
badNode = Root;
}
}
}
badNode.SetBlack();
}
public static void SetBlack(this RBTNode node)
{
node.Color = Color.Black;
}
public static void SetRed(this RBTNode node)
{
node.Color = Color.Red;
}