设A与B分别为两个带有头结点的有序循环链表（所谓有序是指链接点按数据域值大小链接，本题不妨设按数据域值从小到大排列），list1和list2分别为指向两个链表的头指针。请写出将这两个链表合并为一个带头结点的有序循环链表的算法。-Let A and B are two ordered circular list with a header node (the so-called orderly clicking the link refers to the size of the data field value links, this question may wish to set the value according to the data field in ascending order), list1 and list2 respectively to point to two lists of head pointer. Please write the two lists into a single head node ordered circular list of algorithms.