循环单链表是单链表的另一种形式，其结构特点是链表中的最后一个结点的指针域不再是结束标记，而是指向整个链表的第一个结点，从而使链表形成一个环。

问：带头结点的循环单链表的插入、删除算法如何写？-List is a single cycle of a single list of another form, its structure is characterized by a list of the last node pointer domain is no longer a closing tag, but at the entire list of the first node, so that chain table to form a ring. Q: take the lead in the cycle of single-node list of the insert, delete algorithm how to write?