对任意给定的二叉树（顶点数自定）建立它的二叉链表存贮结构，并利用栈的五种基本运算（置空栈、进栈、出栈、取栈顶元素、判栈空）实现二叉树的先序、中序、后序三种周游，

代码说明：

对任意给定的二叉树（顶点数自定）建立它的二叉链表存贮结构，并利用栈的五种基本运算（置空栈、进栈、出栈、取栈顶元素、判栈空）实现二叉树的先序、中序、后序三种周游，输出三种周游的结果。- To wilfully assigns two forks the tree (to go against points from to decide) establishes it two to fork the chain table storage structure, and (sets at spatial stack after the stack five kind of fundamental operations, enters stack, sends out of the warehouse, takes stack top element, sentences stack to be spatial) realizes two forks the tree first the foreword, center the foreword, the foreword three kinds travels around, outputs the result which three kinds travels around.