private void CaseSixRotationDelete(MyRedBlackTreeNode <T> node)
{
var sibling = GetSibling(node);
if (node.IsDoubleBlack && sibling != null &&
sibling.Color == RedBlackTreeNodeColor.Black)
{
bool isRotated = false;
if (sibling?.Right?.Color == RedBlackTreeNodeColor.Red && sibling.Left != null &&
sibling.Parent.Right == sibling)
{
RightRightRotation(sibling.Right);
isRotated = true;
sibling.Right.Color = RedBlackTreeNodeColor.Black;
}
else if (sibling?.Left?.Color == RedBlackTreeNodeColor.Red && sibling.Right != null &&
sibling.Parent.Left == sibling)
{
LeftLeftRotation(sibling.Left);
isRotated = true;
sibling.Left.Color = RedBlackTreeNodeColor.Black;
}
if (isRotated)
{
sibling.Color = node.Parent.Color;
node.Parent.Color = RedBlackTreeNodeColor.Black;
node.IsDoubleBlack = false;
}
}
}
private void LeftLeftRotation(MyRedBlackTreeNode <T> root)
{
var parentParent = root.Parent.Parent;
if (parentParent.Parent != null)
{
if (parentParent.Parent.Left == parentParent)
{
parentParent.Parent.Left = root.Parent;
}
else
{
parentParent.Parent.Right = root.Parent;
}
root.Parent.Parent = parentParent.Parent;
}
else
{
Root = root.Parent;
root.Parent.Parent = null;
}
parentParent.Left = root.Parent.Right;
parentParent.Left.Parent = parentParent;
root.Parent.Right = parentParent;
parentParent.Parent = root.Parent;
if (parentParent == Root)
{
Root = root.Parent;
}
}
private void CaseFiveRotationDelete(MyRedBlackTreeNode <T> node)
{
var sibling = GetSibling(node);
if (node.IsDoubleBlack && sibling != null &&
sibling.Color == RedBlackTreeNodeColor.Black)
{
if (sibling.Parent?.Right == sibling &&
sibling.Left?.Color == RedBlackTreeNodeColor.Red &&
sibling.Right?.Color == RedBlackTreeNodeColor.Black)
{
RightLeftRotation(sibling.Left);
sibling.Color = RedBlackTreeNodeColor.Red;
sibling.Parent.Color = RedBlackTreeNodeColor.Black;
}
else if (sibling.Parent?.Left == sibling &&
sibling.Right?.Color == RedBlackTreeNodeColor.Red &&
sibling.Left?.Color == RedBlackTreeNodeColor.Black)
{
LeftRightRotation(sibling.Right);
sibling.Color = RedBlackTreeNodeColor.Red;
sibling.Parent.Color = RedBlackTreeNodeColor.Black;
}
}
CaseSixRotationDelete(node);
}
private void RemoveDoubleBlack(MyRedBlackTreeNode <T> node)
{
Count--;
if (node == Root)
{
Root = null;
return;
}
var isRight = node.Parent.Right == node;
if (isRight)
{
node.Parent.Right = node.Right;
}
else
{
node.Parent.Left = node.Right;
}
node.Right.Parent = node.Parent;
node.Right.IsDoubleBlack = true;
CaseOneRotationDelete(node.Right);
node.Right = null;
node.Parent = null;
}
public MyRedBlackTreeNode(T data)
{
Data = data;
Color = RedBlackTreeNodeColor.Red;
Left = new MyRedBlackTreeNode <T>(true, this);
Right = new MyRedBlackTreeNode <T>(true, this);
}
private void RemoveBlackWithSingleRedChild(MyRedBlackTreeNode <T> node, bool isSingleLeft)
{
if (Root == node)
{
Root = isSingleLeft ? node.Left : node.Right;
Root.Color = RedBlackTreeNodeColor.Black;
Root.Parent = null;
}
else
{
if (node.Parent.Right == node)
{
node.Parent.Right = isSingleLeft ? node.Left : node.Right;
}
else
{
node.Parent.Left = isSingleLeft ? node.Left : node.Right;
}
if (isSingleLeft)
{
node.Left.Parent = node.Parent;
node.Left.Color = RedBlackTreeNodeColor.Black;
}
else
{
node.Right.Parent = node.Parent;
node.Right.Color = RedBlackTreeNodeColor.Black;
}
node.Parent = null;
node.Right = null;
}
Count--;
}
public void Remove(MyRedBlackTreeNode <T> node)
{
if (node == null)
{
throw new ArgumentNullException();
}
bool isSingleLeft = node.Left.Color == RedBlackTreeNodeColor.Red && node.Right.IsNull;
bool isSingleRight = node.Right.Color == RedBlackTreeNodeColor.Red && node.Left.IsNull;
if (!node.Left.IsNull && !node.Right.IsNull)
{
var successor = FindInOrderSuccessor(node);
SwapWithSuccessor(node, successor);
Remove(node);
}
else if (node.Color == RedBlackTreeNodeColor.Red)
{
RemoveSingleRed(node);
}
else if (node.Color == RedBlackTreeNodeColor.Black &&
(isSingleLeft || isSingleRight))
{
RemoveBlackWithSingleRedChild(node, isSingleLeft);
}
else
{
RemoveDoubleBlack(node);
}
}
public MyRedBlackTreeNode(T data,
RedBlackTreeNodeColor color,
MyRedBlackTreeNode <T> left,
MyRedBlackTreeNode <T> right) : this(data, color)
{
Left = left;
Right = right;
}
public MyRedBlackTreeNode(T data,
RedBlackTreeNodeColor color,
MyRedBlackTreeNode <T> left,
MyRedBlackTreeNode <T> right,
MyRedBlackTreeNode <T> parent) : this(data, color, left, right)
{
Parent = parent;
}
private void SwapWithSuccessor(MyRedBlackTreeNode <T> node, MyRedBlackTreeNode <T> successor)
{
var parentNode = node.Parent;
if (parentNode != null)
{
if (parentNode.Left == node)
{
parentNode.Left = successor;
}
else
{
parentNode.Right = successor;
}
}
var parentSuccessor = successor.Parent;
if (parentSuccessor.Left == successor)
{
parentSuccessor.Left = node;
}
else
{
parentSuccessor.Right = node;
}
successor.Parent = parentNode;
node.Parent = parentSuccessor;
var nodeLeft = node.Left;
node.Left = successor.Left;
successor.Left = nodeLeft;
node.Left.Parent = node;
successor.Left.Parent = successor;
var nodeRight = node.Right;
node.Right = successor.Right;
successor.Right = nodeRight;
node.Right.Parent = node;
successor.Right.Parent = successor;
var color = node.Color;
node.Color = successor.Color;
successor.Color = color;
if (Root == node)
{
Root = successor;
}
}
private MyRedBlackTreeNode <T> FindInOrderSuccessor(MyRedBlackTreeNode <T> root)
{
var next = root.Right;
while (!next.IsNull && !next.Left.IsNull)
{
next = next.Left;
}
return(next);
}
private void CaseOneRotationDelete(MyRedBlackTreeNode <T> node)
{
if (node == Root && node.IsDoubleBlack)
{
node.Color = RedBlackTreeNodeColor.Black;
node.IsDoubleBlack = false;
}
else
{
CaseTwoRotationDelete(node);
}
}
private MyRedBlackTreeNode <T> GetSibling(MyRedBlackTreeNode <T> node)
{
if (node == null || node.Parent == null)
{
return(null);
}
if (node.Parent.Left == node)
{
return(node.Parent.Right);
}
return(node.Parent.Left);
}
public void Insert(T data)
{
if (Root == null)
{
Root = new MyRedBlackTreeNode <T>(data, RedBlackTreeNodeColor.Black);
}
else
{
InsertHelper(Root, data);
}
Count++;
}
private void LeftRightRotation(MyRedBlackTreeNode <T> root)
{
var parentParent = root.Parent.Parent;
var left = root.Left;
root.Left = root.Parent;
parentParent.Left = root;
root.Left.Right = left;
root.Parent = parentParent;
root.Left.Parent = root;
root.Left.Right.Parent = root.Left;
}
private void RemoveSingleRed(MyRedBlackTreeNode <T> node)
{
if (node.Parent.Left == node)
{
node.Parent.Left = node.Right;
}
else
{
node.Parent.Right = node.Right;
}
node.Right.Parent = node.Parent;
node.Right = null;
node.Parent = null;
Count--;
}
private void CaseThreeRotationDelete(MyRedBlackTreeNode <T> node)
{
var sibling = GetSibling(node);
if (node.IsDoubleBlack && sibling != null &&
node.Parent?.Color == RedBlackTreeNodeColor.Black && sibling.Color == RedBlackTreeNodeColor.Black &&
sibling.Left?.Color == RedBlackTreeNodeColor.Black && sibling.Right?.Color == RedBlackTreeNodeColor.Black)
{
node.IsDoubleBlack = false;
node.Parent.IsDoubleBlack = true;
sibling.Color = RedBlackTreeNodeColor.Red;
CaseOneRotationDelete(node.Parent);
}
CaseFourRotationDelete(node);
}
private void CaseFourRotationDelete(MyRedBlackTreeNode <T> node)
{
var sibling = GetSibling(node);
if (node.IsDoubleBlack && sibling != null &&
node.Parent.Color == RedBlackTreeNodeColor.Red && sibling.Color == RedBlackTreeNodeColor.Black &&
sibling.Left.Color == RedBlackTreeNodeColor.Black && sibling.Right.Color == RedBlackTreeNodeColor.Black)
{
node.IsDoubleBlack = false;
node.Parent.Color = RedBlackTreeNodeColor.Black;
sibling.Color = RedBlackTreeNodeColor.Red;
}
else
{
CaseFiveRotationDelete(node);
}
}
private MyRedBlackTreeNode <T> FindHelper(T data, MyRedBlackTreeNode <T> root)
{
if (root.IsNull)
{
return(null);
}
var compared = data.CompareTo(root.Data);
if (compared == 0 && !root.IsNull)
{
return(root);
}
if (compared < 0)
{
return(FindHelper(data, root.Left));
}
return(FindHelper(data, root.Right));
}
private void CaseTwoRotationDelete(MyRedBlackTreeNode <T> node)
{
var sibling = GetSibling(node);
if (node.IsDoubleBlack && sibling != null &&
node.Parent.Color == RedBlackTreeNodeColor.Black && sibling.Color == RedBlackTreeNodeColor.Red &&
sibling.Left?.Color == RedBlackTreeNodeColor.Black && sibling.Right?.Color == RedBlackTreeNodeColor.Black)
{
if (node.Parent.Left == node)
{
RightRightRotation(sibling.Right);
}
else
{
LeftLeftRotation(sibling.Left);
}
sibling.Color = RedBlackTreeNodeColor.Black;
node.Parent.Color = RedBlackTreeNodeColor.Red;
}
CaseThreeRotationDelete(node);
}
private bool IsValidHelper(MyRedBlackTreeNode <T> root,
MyRedBlackTreeNode <T> parent,
List <int> countBlacks, int currentCount)
{
if (root == null || root.Parent != parent)
{
return(false);
}
if (parent != null && parent.Left != root && parent?.Right != root)
{
return(false);
}
if (parent?.Color == RedBlackTreeNodeColor.Red &&
root.Color == RedBlackTreeNodeColor.Red)
{
return(false);
}
if (root.IsNull)
{
countBlacks.Add(currentCount);
return(true);
}
if (root.Color == RedBlackTreeNodeColor.Black)
{
currentCount++;
}
if (!IsValidHelper(root.Left, root, countBlacks, currentCount))
{
return(false);
}
if (!IsValidHelper(root.Right, root, countBlacks, currentCount))
{
return(false);
}
return(true);
}
public MyRedBlackTreeNode(T data, RedBlackTreeNodeColor color,
MyRedBlackTreeNode <T> parent) : this(data)
{
Color = color;
Parent = parent;
}
public MyRedBlackTreeNode(bool isNull, MyRedBlackTreeNode <T> parent)
{
IsNull = isNull;
Parent = parent;
Color = RedBlackTreeNodeColor.Black;
}
private void InsertHelper(MyRedBlackTreeNode <T> root, T data)
{
MyRedBlackTreeNode <T> node = null;
if (root.IsNull)
{
node = new MyRedBlackTreeNode <T>(data, RedBlackTreeNodeColor.Red, root.Parent);
if (root.Parent.Left == root)
{
root.Parent.Left = node;
}
else
{
root.Parent.Right = node;
}
root.Color = RedBlackTreeNodeColor.Red;
}
var compared = data.CompareTo(root.Data);
if (compared <= 0 && root.Left != null)
{
InsertHelper(root.Left, data);
}
else if (root.Right != null)
{
InsertHelper(root.Right, data);
}
if (root.Parent == null || root.Parent.Color == RedBlackTreeNodeColor.Black)
{
if (node != null)
{
root.Parent = null;
}
return;
}
var otherSibling = root.Parent.Parent.Left == root.Parent ?
root.Parent.Parent.Right : root.Parent.Parent.Left;
if (otherSibling.Color == RedBlackTreeNodeColor.Red)
{
otherSibling.Color = RedBlackTreeNodeColor.Black;
otherSibling.Parent.Color = otherSibling.Parent == Root ? RedBlackTreeNodeColor.Black : RedBlackTreeNodeColor.Red;
root.Parent.Color = RedBlackTreeNodeColor.Black;
}
else if (root.Color == RedBlackTreeNodeColor.Red)
{
root = node ?? root;
if (root.Parent.Right == root && root.Parent.Parent.Left == root.Parent)
{
LeftRightRotation(root);
root = root.Left;
}
if (root.Parent.Left == root && root.Parent.Parent.Right == root.Parent)
{
RightLeftRotation(root);
root = root.Right;
}
if (root.Parent.Left == root && root.Parent.Parent.Left == root.Parent)
{
LeftLeftRotation(root);
root.Parent.Right.Color = RedBlackTreeNodeColor.Red;
root.Parent.Color = RedBlackTreeNodeColor.Black;
}
if (root.Parent.Right == root && root.Parent.Parent.Right == root.Parent)
{
RightRightRotation(root);
root.Parent.Color = RedBlackTreeNodeColor.Black;
root.Parent.Left.Color = RedBlackTreeNodeColor.Red;
}
}
}