对二叉树的删除、复制、中序遍历采用递归方式实现。

　　层序遍历采用辅助队列数据结构完成，为了计算层高，

　　使用了两个队列，交替的向两队列中插入相邻的两层，

　　这样完成层高的统计。-On the binary tree delete, copy, preorder recursive manner.

Traversal sequence complete with assisted queue data structure, in order to calculate storey,

The use of two queues, alternating the two adjacent layers inserted in the queue,

This completes storey statistics.