建立二叉树

代码说明：

  同济大学课程设计中的一道题! 要求能够输入树的各个结点，并能够输出用不同方法遍历的遍历序列；分别建立建立二叉树存储结构的的输入函数、输出层序遍历序列的函数、输出先序遍历序列的函数.(Tongji University in curriculum design, the one that! Tree request to enter the various nodes, and can output using different methods traverse the traversal sequence; Binary Tree set up to establish the structure of the storage function input and output sequence traversal sequence of function, the output preorder sequence of function.)