public void Delete(int data)
        {
            TreeNode parent  = this.root;
            TreeNode current = this.root;
            bool     isleft  = false;

            if (root == null)
            {
                return;
            }
            while (current != null && current.GetData() != data)
            {
                parent = current;
                if (current.GetData() < data)
                {
                    current = current.GetLeft();
                    isleft  = true;
                }
                else
                {
                    current = current.GetRight();
                    isleft  = false;
                }
            }
            if (current == null)
            {
                return;
            }

            if (current.GetRight() == null && current.GetLeft() == null)
            {
                if (root == current)
                {
                    root = null;
                }
                else
                {
                    if (isleft == true)
                    {
                        current.SetLeft(null);
                    }
                    else
                    {
                        current.SetRight(null);
                    }
                }
            }
            else if (current.GetLeft() == null)
            {
                if (root == current)
                {
                    root = current.GetRight();
                }
                else if (isleft)
                {
                    parent.SetLeft(current.GetRight());
                }
                else
                {
                    parent.SetRight(current.GetRight());
                }
            }
            else if (current.GetRight() == null)
            {
                if (root == current)
                {
                    root = current.GetLeft();
                }
                else if (isleft)
                {
                    parent.SetLeft(current.GetLeft());
                }
                else
                {
                    parent.SetRight(current.GetLeft());
                }
            }
            else
            {
                TreeNode successor = getSuccessor(current);
                if (current == root)
                {
                    root = successor;
                }
                else if (isleft)
                {
                    parent.SetLeft(successor);
                }
                else
                {
                    parent.SetRight(successor);
                }
                successor.SetLeft(current.GetLeft());
            }
        }