public int Next()
{
TreeAgainNode current = stack.Pop();
FindNext(current.Right);
return(current.Data);
}
private TreeAgainNode FlipColor(TreeAgainNode node)
{
node.Color = TreeAgainNodeColor.Red;
node.Left.Color = TreeAgainNodeColor.Black;
node.Right.Color = TreeAgainNodeColor.Black;
return(node);
}
private void FindNext(TreeAgainNode node)
{
if (node == null)
{
return;
}
stack.Push(node);
FindNext(node.Left);
}
private TreeAgainNode RotateRight(TreeAgainNode node)
{
TreeAgainNode old = node;
node = node.Left;
node.Color = old.Color;
old.Left = node.Right;
node.Right = old;
old.Color = TreeAgainNodeColor.Red;
return(node);
}
private TreeAgainNode CheckBalance(TreeAgainNode node)
{
if (IsRed(node.Right) && !IsRed(node.Left))
{
node = RotateLeft(node);
}
if (IsRed(node.Left) && IsRed(node.Left.Left))
{
node = RotateRight(node);
}
if (IsRed(node.Left) && IsRed(node.Right))
{
node = FlipColor(node);
}
return(node);
}
private TreeAgainNode CheckBalance(TreeAgainNode node)
{
if (IsRed(node.Right) && !IsRed(node.Left))
{
node = RotateLeft(node);
}
if (IsRed(node.Left) && IsRed(node.Left.Left))
{
node = RotateRight(node);
}
if (IsRed(node.Left) && IsRed(node.Right))
{
node = FlipColor(node);
}
return node;
}
private TreeAgainNode DoAdd(TreeAgainNode node, int x)
{
if (node == null)
{
node = new TreeAgainNode(x);
return(node);
}
if (x < node.Data)
{
node.Left = DoAdd(node.Left, x);
}
else
{
node.Right = DoAdd(node.Right, x);
}
return(CheckBalance(node));
}
private TreeAgainNode FlipColor(TreeAgainNode node)
{
node.Color = TreeAgainNodeColor.Red;
node.Left.Color = TreeAgainNodeColor.Black;
node.Right.Color = TreeAgainNodeColor.Black;
return node;
}
public void Add(int x)
{
root = DoAdd(root, x);
}
private TreeAgainNode RotateRight(TreeAgainNode node)
{
TreeAgainNode old = node;
node = node.Left;
node.Color = old.Color;
old.Left = node.Right;
node.Right = old;
old.Color = TreeAgainNodeColor.Red;
return node;
}
public TreeAgainIterator(TreeAgainNode root)
{
stack = new Stack<TreeAgainNode>();
FindNext(root);
}
public TreeAgainIterator(TreeAgainNode root)
{
stack = new Stack <TreeAgainNode>();
FindNext(root);
}
private bool IsRed(TreeAgainNode node)
{
return(node != null && node.Color == TreeAgainNodeColor.Red);
}
private void FindNext(TreeAgainNode node)
{
if (node == null)
{
return;
}
stack.Push(node);
FindNext(node.Left);
}
private bool IsRed(TreeAgainNode node)
{
return (node != null && node.Color == TreeAgainNodeColor.Red);
}
private TreeAgainNode DoAdd(TreeAgainNode node, int x)
{
if (node == null)
{
node = new TreeAgainNode(x);
return node;
}
if (x < node.Data)
{
node.Left = DoAdd(node.Left, x);
}
else
{
node.Right = DoAdd(node.Right, x);
}
return CheckBalance(node);
}
public void Add(int x)
{
root = DoAdd(root, x);
}
