说明：  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)
(Manually enter each node to build a binary tree (recursively), common binary tree inorder and postorder traversal (recursive), the sequence of clues (recursively), threaded binary preorder and preorder (recursive), the clues in the binary sequence traversal (non-stack, non-recursive),Level traversal (using queues))