（数据结构）二叉树相关算法，包括按先序扩展序列建立二叉树，二叉树的先序、中序、后序的递归、非递归算法，层次非递归算法以及求二叉树的深度-(Data structure) binary tree algorithm, including the expansion of the sequence of the first sequence to the establishment of a binary tree, binary tree preorder, inorder, postorder