/// <summary>
    /// 二叉查找树类  
    /// IComparable：使用此进行限制是为了实现 两个实体类之间按>，=，<进行比较
    /// </summary>
    /// <typeparam name="E"></typeparam>
    class BST<E> where E : IComparable<E>
    {
        /// <summary>
        /// 节点类
        /// </summary>
        private class Node
        {
            public E e;
            public Node left;
            public Node right;

            public Node(E e)
            {
                this.e = e;
                left = null;
                right = null;

            }
        }

        private Node root;
        private int N;
        public BST()
        {
            root = null;
            N = 0;
        }


        public int Count
        {
            get
            {
                return N;
            }
        }
        public bool IsEmpty
        {
            get
            {
                return N == 0;
            }
        }
         
    }