树的层次遍历。

题目：给定一棵用二叉链表表示的二叉树，其中的指针t指向根结点，试写出从根开始，按层次遍历二叉树的算法，同层的结点按从左至右的次序访问。-The level of the tree traversal. Title: given a list with that of the binary tree, in which the indicators point to root node t try to write from the root to start, according to the level of binary tree traversal algorithms, the same floor by the node from the left to right order of the visit.