public static void RotateLeft(this RedBlackTree.Node b)
{
if (b == null)
{
throw new ArgumentException("node doesn't equal null");
}
var d = b.Right;
if (b == null)
{
throw new ArgumentException("parent node doesn't equal null");
}
if (d.Parent.Right != d)
{
throw new ArgumentException("If you use left rotate node must contain right child");
}
var high = d.Parent.Parent;
var c = d.Left;
b.SetRight(c);
if (high?.Left == b)
{
high.SetLeft(d);
}
else if (high?.Right == b)
{
high.SetRight(d);
}
d.SetLeft(b);
}
public static RedBlackTree.Node Uncle(this RedBlackTree.Node nd)
{
if (IsLeftChild(nd.Parent))
{
return(nd.Parent.Parent.Right);
}
if (IsRightChild(nd.Parent))
{
return(nd.Parent.Parent.Left);
}
throw new Exception("Invalid state");
}
public static RedBlackTree.Node Sibling(this RedBlackTree.Node nd)
{
if (nd.Parent == null)
{
throw new InvalidOperationException("parent is null");
}
if (nd.Parent.Left == nd)
{
return(nd.Parent.Right);
}
if (nd.Parent.Right == nd)
{
return(nd.Parent.Left);
}
throw new ArgumentException("invalid state");
}
public static bool HasRedUncle(this RedBlackTree.Node nd)
{
if (nd?.Parent?.Parent == null)
{
return(false);
}
if (nd.Parent.Parent.Left == nd.Parent)
{
return(nd.Parent.Parent.Right?.Color == RedBlackTree.Color.Red);
}
if (nd.Parent.Parent.Right == nd.Parent)
{
return(nd.Parent.Parent.Left?.Color == RedBlackTree.Color.Red);
}
throw new ArgumentException("state invalid, parent not parent for " + nameof(nd));
}
public static bool IsLeftChild(this RedBlackTree.Node nd) => nd.Parent.Left == nd;
public static bool IsRightChild(this RedBlackTree.Node nd) => nd.Parent.Right == nd;