二叉树的几种操作，包括递归先序建立二叉树、先序遍历、中序遍历、后序遍历、非递归的各种遍历、计算叶子节点数目和所有节点数目，使用队列实现层次遍历。供研究和学习基本算法者使用-Binary tree of several operations, including the establishment of binary tree recursive first order, first traversal, in order traversal, postorder traversal, a var