编程任务：

对于给定的树，以根结点为起点，对树实现非递归方式广度优先搜索，输出广度优

先搜索序列

 数据输入：

由文件input.txt给出输入数据。第1行有1个正整数n，表示给定的二叉树有n个顶

点，编号为1，2，…，n。接下来的n行中，每行有3个正整数a,b,c，分别表示编号为a的结

点的左儿子结点编号为b，右儿子结点编号为c，0表示没有儿子。各结点信息按照层序列表

的顺序给出。-Programming tasks: For a given of the tree, in order to root node as a starting point, right tree implementation non-recursive way of breadth-first search, the output breadth-first search sequence 　Data Input: by the file input.txt given input data. First 1 Line There are 1 positive integer n, represents a given binary tree with n vertices, numbered 1,2, ..., n. The following n row, each line has three positive integers a, b, c, respectively indicate the reference numbers as a, node point of a left son of node point number is b, right-his son node point number as the c, 0 indicates no sons. Each of the balance point information in accordance with the layer sequence the order of tables are given.