/// <summary>
/// Fix up after inserting
/// </summary>
/// <param name="root">Reference to root</param>
/// <param name="nodeX">Reference to node which was inserted</param>
/// <returns>Reference to root</returns>
private RedBlackBinaryTreeNode <T> InsertFixUp(RedBlackBinaryTreeNode <T> root, RedBlackBinaryTreeNode <T> nodeX)
{
while (nodeX != root && nodeX._parent._color == BinaryTreeColor.Red)
{
if (nodeX._parent == nodeX._parent._parent.Left as RedBlackBinaryTreeNode <T> )
{
var nodeY = nodeX._parent._parent.Right as RedBlackBinaryTreeNode <T>;
if (nodeY != null && nodeY._color == BinaryTreeColor.Red)
{
nodeX._parent._color = BinaryTreeColor.Black;
nodeY._color = BinaryTreeColor.Black;
nodeX._parent._parent._color = BinaryTreeColor.Red;
nodeX = nodeX._parent._parent;
}
else
{
if (nodeX == nodeX._parent.Right as RedBlackBinaryTreeNode <T> )
{
nodeX = nodeX._parent;
root = RotateLeft(root, nodeX);
}
nodeX._parent._color = BinaryTreeColor.Black;
nodeX._parent._parent._color = BinaryTreeColor.Red;
root = RotateRight(root, nodeX._parent._parent);
}
}
else
{
var x = nodeX._parent._parent.Left as RedBlackBinaryTreeNode <T>;
if (x != null && x._color == BinaryTreeColor.Red)
{
nodeX._parent._color = BinaryTreeColor.Black;
x._color = BinaryTreeColor.Black;
nodeX._parent._parent._color = BinaryTreeColor.Red;
nodeX = nodeX._parent._parent;
}
else
{
if (nodeX == nodeX._parent.Left as RedBlackBinaryTreeNode <T> )
{
nodeX = nodeX._parent;
root = RotateRight(root, nodeX);
}
nodeX._parent._color = BinaryTreeColor.Black;
nodeX._parent._parent._color = BinaryTreeColor.Red;
root = RotateLeft(root, nodeX._parent._parent);
}
}
root._color = BinaryTreeColor.Black;
}
return(root);
}
/// <summary>
/// Finds sibling of <paramref name="node"/>
/// </summary>
/// <param name="node"></param>
/// <returns>Sibling of <paramref name="node"/></returns>
private RedBlackBinaryTreeNode <T> GetSibling(RedBlackBinaryTreeNode <T> node)
{
var parent = node._parent;
return(parent == null
? null
: node.Equals(parent.Left)
? parent.Right as RedBlackBinaryTreeNode <T>
: parent.Left as RedBlackBinaryTreeNode <T>);
}
/// <inheritdoc/>
public override void Add(T item)
{
if (ReferenceEquals(Root, null))
{
Root = new RedBlackBinaryTreeNode <T>(item);
Count = 1;
return;
}
if (Contains(item))
{
return;
}
Root = Root.Insert(item);
Count++;
}
/// <summary>
/// Right rotate of <paramref name="node"/>
/// </summary>
/// <param name="root">Reference to root</param>
/// <param name="node">Reference to node to rotate</param>
/// <returns>Reference to <paramref name="root"/></returns>
private RedBlackBinaryTreeNode <T> RotateRight(RedBlackBinaryTreeNode <T> root, RedBlackBinaryTreeNode <T> node)
{
var X = node.Left as RedBlackBinaryTreeNode <T>;
node.Left = X.Right;
if (X.Right != null)
{
(X.Right as RedBlackBinaryTreeNode <T>)._parent = node;
}
if (X != null)
{
X._parent = node._parent;
}
if (node._parent == null)
{
root = X;
}
if (node._parent != null)
{
if (node == node._parent.Right as RedBlackBinaryTreeNode <T> )
{
node._parent.Right = X;
}
if (node == node._parent.Left as RedBlackBinaryTreeNode <T> )
{
node._parent.Left = X;
}
}
X.Right = node;
if (node != null)
{
node._parent = X;
}
return(root);
}
/// <summary>
/// Left rotate of <paramref name="node"/>
/// </summary>
/// <param name="root">Reference to root</param>
/// <param name="node">Reference to node to rotate</param>
/// <returns>Reference to <paramref name="root"/></returns>
private RedBlackBinaryTreeNode <T> RotateLeft(RedBlackBinaryTreeNode <T> root, RedBlackBinaryTreeNode <T> node)
{
var nodeY = node.Right as RedBlackBinaryTreeNode <T>;
node.Right = nodeY.Left;
if (nodeY.Left != null)
{
(nodeY.Left as RedBlackBinaryTreeNode <T>)._parent = node;
}
if (nodeY != null)
{
nodeY._parent = node._parent;
}
if (node._parent == null)
{
root = nodeY;
}
if (nodeY._parent != null)
{
if (node == node._parent.Left as RedBlackBinaryTreeNode <T> )
{
node._parent.Left = nodeY;
}
else
{
node._parent.Right = nodeY;
}
}
nodeY.Left = node;
if (node != null)
{
node._parent = nodeY;
}
return(root);
}
private RedBlackBinaryTreeNode <T> InternalInsert(RedBlackBinaryTreeNode <T> root, T value)
{
var newNode = new RedBlackBinaryTreeNode <T>(value);
RedBlackBinaryTreeNode <T> nodeY = null;
var nodeX = root;
while (nodeX != null)
{
nodeY = nodeX;
if (newNode < nodeX)
{
nodeX = nodeX.Left as RedBlackBinaryTreeNode <T>;
}
else
{
nodeX = nodeX.Right as RedBlackBinaryTreeNode <T>;
}
}
newNode._parent = nodeY;
if (nodeY == null)
{
root = newNode;
}
else if (newNode < nodeY)
{
nodeY.Left = newNode;
}
else
{
nodeY.Right = newNode;
}
newNode.Left = null;
newNode.Right = null;
newNode._color = BinaryTreeColor.Red;
root = InsertFixUp(root, newNode);
return(root);
}
/// <summary> /// Finds grandparent of <paramref name="node"/> /// </summary> /// <param name="node"></param> /// <returns>Grandparent of <paramref name="node"/></returns> private RedBlackBinaryTreeNode <T> GetGrandparent(RedBlackBinaryTreeNode <T> node) => node?._parent?._parent;
/// <summary>
/// Finds uncle of <paramref name="node"/>
/// </summary>
/// <param name="node"></param>
/// <returns>Uncle of <paramref name="node"/></returns>
private RedBlackBinaryTreeNode <T> GetUncle(RedBlackBinaryTreeNode <T> node)
{
var parent = node._parent;
return(GetSibling(parent));
}
private RedBlackBinaryTreeNode <T> InternalRemove(RedBlackBinaryTreeNode <T> root, T value)
{
var item = FindNode(root, value) as RedBlackBinaryTreeNode <T>;
RedBlackBinaryTreeNode <T> nodeY;
if (item.Left == null && item.Right == null)
{
if (item == root)
{
return(null);
}
nodeY = item._parent;
if (nodeY.Left as RedBlackBinaryTreeNode <T> == item)
{
nodeY.Left = null;
}
else
{
nodeY.Right = null;
}
}
else if (item.Left == null)
{
nodeY = item._parent;
if (nodeY == null)
{
return(item.Right as RedBlackBinaryTreeNode <T>);
}
if (nodeY.Left as RedBlackBinaryTreeNode <T> == item)
{
nodeY.Left = item.Right;
}
else
{
nodeY.Right = item.Right;
}
}
else if (item.Right == null)
{
nodeY = item._parent;
if (nodeY == null)
{
return(item.Left as RedBlackBinaryTreeNode <T>);
}
if (nodeY.Left as RedBlackBinaryTreeNode <T> == item)
{
nodeY.Left = item.Left;
}
else
{
nodeY.Right = item.Left;
}
}
else
{
var nodeX = item.Left.Max() as RedBlackBinaryTreeNode <T>;
item.Data = nodeX.Data;
nodeY = nodeX._parent;
if (nodeY.Left as RedBlackBinaryTreeNode <T> == nodeX)
{
nodeY.Left = nodeX.Left;
if (nodeX._color == BinaryTreeColor.Black)
{
root = DeleteFixUp(root, nodeY.Left as RedBlackBinaryTreeNode <T>);
}
}
else
{
nodeY.Right = nodeX.Left;
if (nodeX._color == BinaryTreeColor.Black)
{
root = DeleteFixUp(root, nodeY.Right as RedBlackBinaryTreeNode <T>);
}
}
}
return(root);
}
/// <summary>
/// Fix up after removing
/// </summary>
/// <param name="root">Reference to root</param>
/// <param name="nodeX">Reference to node which helps to fix up</param>
/// <returns>Reference to root</returns>
private RedBlackBinaryTreeNode <T> DeleteFixUp(RedBlackBinaryTreeNode <T> root, RedBlackBinaryTreeNode <T> nodeX)
{
while (nodeX != null && nodeX != root && nodeX._color == BinaryTreeColor.Black)
{
if (nodeX == nodeX._parent.Left as RedBlackBinaryTreeNode <T> )
{
var nodeW = nodeX._parent.Right as RedBlackBinaryTreeNode <T>;
if (nodeW._color == BinaryTreeColor.Red)
{
nodeW._color = BinaryTreeColor.Black;
nodeX._parent._color = BinaryTreeColor.Red;
root = RotateLeft(root, nodeX._parent);
nodeW = nodeX._parent.Right as RedBlackBinaryTreeNode <T>;
}
if ((nodeW?.Left as RedBlackBinaryTreeNode <T>)?._color == BinaryTreeColor.Black &&
(nodeW.Right as RedBlackBinaryTreeNode <T>)?._color == BinaryTreeColor.Black)
{
nodeW._color = BinaryTreeColor.Red;
nodeX = nodeX._parent;
}
else if ((nodeW.Right as RedBlackBinaryTreeNode <T>)._color == BinaryTreeColor.Black)
{
(nodeW.Left as RedBlackBinaryTreeNode <T>)._color = BinaryTreeColor.Black;
nodeW._color = BinaryTreeColor.Red;
root = RotateRight(root, nodeW);
nodeW = nodeX._parent.Right as RedBlackBinaryTreeNode <T>;
}
nodeW._color = nodeX._parent._color;
nodeX._parent._color = BinaryTreeColor.Black;
(nodeW.Right as RedBlackBinaryTreeNode <T>)._color = BinaryTreeColor.Black;
root = RotateLeft(root, nodeX._parent);
nodeX = root;
}
else
{
var w = nodeX._parent.Left as RedBlackBinaryTreeNode <T>;
if (w._color == BinaryTreeColor.Red)
{
w._color = BinaryTreeColor.Black;
nodeX._parent._color = BinaryTreeColor.Red;
root = RotateRight(root, nodeX._parent);
w = nodeX._parent.Left as RedBlackBinaryTreeNode <T>;
}
if ((w.Right as RedBlackBinaryTreeNode <T>)._color == BinaryTreeColor.Black &&
(w.Left as RedBlackBinaryTreeNode <T>)._color == BinaryTreeColor.Black)
{
w._color = BinaryTreeColor.Black;
nodeX = nodeX._parent;
}
else if ((w.Left as RedBlackBinaryTreeNode <T>)._color == BinaryTreeColor.Black)
{
(w.Right as RedBlackBinaryTreeNode <T>)._color = BinaryTreeColor.Black;
w._color = BinaryTreeColor.Red;
root = RotateLeft(root, w);
w = nodeX._parent.Left as RedBlackBinaryTreeNode <T>;
}
w._color = nodeX._parent._color;
nodeX._parent._color = BinaryTreeColor.Black;
(w.Left as RedBlackBinaryTreeNode <T>)._color = BinaryTreeColor.Black;
root = RotateRight(root, nodeX._parent);
nodeX = root;
}
}
if (nodeX != null)
{
nodeX._color = BinaryTreeColor.Black;
}
return(root);
}
