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,Set up A and B respectively with the first two nodes in an orderly circulation list (so-called orderly means the link click data link threshold size, the title may be set up by the data field values from small to large order), list1 and List2 list were two of the indicators point. Please write a list of these two merged into a single node to take the lead in the orderly cycle of the algorithm list