建立一棵二叉树，并对其进行遍历（先序、中序、后序），打印输出遍历结果。 从键盘接受输入（先序），以二叉链表作为存储结构，建立二叉树（以先序来建立），并采用递归算法对其进行遍历（先序、中序、后序），将遍历结果打印输出-Create a binary tree, and traverse the results of its traversal (preorder, inorder, postorder), print output. Accept input from the keyboard (first order), binary list as a storage structure, the establishment of a binary tree (to create) a first-order recursive algorithm and its traversal (preorder, inorder, postorder) traversal results Print export