1.求双向循环链表的长度

2.在双向循环链表指定位置插入一个元素

3.给定双向循环链表中一个结点元素值e，要求将数据y插入到元素e的前面

4.给定双向循环链表中一个结点元素值e，要求将数据y插入到元素e的后面

5.给定双向循环链表中一个结点元素值e，要求将数据y插入到元素e的后面

6.删除双向循环链表中指定位置的元素

7.给定双向循环链表中一个结点元素值e，要求将其对应结点删除

8.给定双向循环链表中一个结点元素值e，要求删除对应结点的直接前驱

9.给定双向循环链表中一个结点元素值e，要求删除对应结点的直接后继

10.求双向循环链表中第i个元素

11.判断双向循环链表H中是否存在元素x，若存在返回1，否则返回0

12.将双向循环链表L就地逆置

13.将双向循环链表逆序输出

14.求双向循环链表H中结点p的直接前驱

15.求双向循环链表H中结点p的直接后继-1. Seek a two-way circular list the length of the

2. In a two-way circular linked list insert an element in the specified location

3. For a given two-way loop in a linked list node element of the value of e, requires that the data y is inserted into the front element e

4. For a given two-way loop in a linked list node element of the value of e, requires that the data y is inserted into the back of element e

5. For a given two-way loop in a linked list node element of the value of e, requires that the data y is inserted into the back of element e

6. Remove the two-way circular linked list of elements in the specified location

7. For a given two-way loop in a linked list node element of the value of e, request to delete the corresponding nodes

8. For a given two-way loop in a linked list node element of the value of e, to delete the corresponding node immediate precursor

9. For a given two-way loop in a linked list node element of the value of e, to delete the correspondi