手动输入各个结点建立二叉树(递归) ,普通二叉树的先序和后序遍历(递归),中序线索化(递归), 线索二叉树的先序和中序遍历(递归),线索二叉树的中序遍历(非栈、非递归), 层次遍历(使用队列),销毁整棵二叉树(递归)-Manually enter each node to build a binary tree (recursively), common binary tree inorder and postorder traversal (recursive), the sequence

数据结构难点，树，实现树的前序中序后序遍历，对初学数据结构很有启发-Data structure difficulty, tree, tree realize after preorder preamble sequence, the data structure is very enlightening for beginners