求二叉搜索树的前驱节点和后继节点

/**
* 前驱元素
* **/
public BSTreeNode<T> Pred(BSTreeNode<T> node) {
	if (node.left != null) {
		return Max(node.left);
	}
	BSTreeNode<T> parent = node.parent;
	while (parent != null && node != parent.right) {
		node = parent;
		parent = node.parent;
	}
	return parent;
}

/**
* 后继元素
* **/
public BSTreeNode<T> Succ(BSTreeNode<T> node) {
	if (node.right != null) {
		return Min(node.right);
	}
	BSTreeNode<T> parent = node.parent;
	while (parent != null && node != parent.left) {
		node = parent;
		parent = node.parent;
	}
	return parent;
}