从左到右及从右到左遍历一个单链表是可能的，其方法是在从左向右遍历的过程中将连接方向逆转，如右图所示。在图中的指针p指向当前正在访问的结点，指针pr指向指针p所指结点的左侧的结点。此时，指针p所指结点左侧的所有结点的链接方向都已逆转。

　　(1) 编写一个算法，从任一给定的位置(pr, p)开始，将指针p右移k个结点。如果p移出链表，则将p置为0，并让pr停留在链表最右边的结点上。

　　(2) 编写一个算法，从任一给定的位置(pr, p)开始，将指针p左移k个结点。如果p移出链表，则将p置为0，并让pr停留在链表最左边的结点上。

-From left to right and right to left traverse a single linked list is possible in from left to right during traversal connection direction reversal, as shown on the right. Pointer p points in the diagram is currently being accessed node pointer PR point to the left side of the pointer p junction referred junction. At this point, the pointer p nodes referred to the left all nodes link direction are reversed. (1) preparation of an algorithm, from a given position (PR, P) start, the pointer p to the right k nodes. If p is removed from the linked list, then p is set to 0, and Pr remain in the linked list of the right-most node. (2) the preparation of an algorithm, from any given position (PR, P) start, the pointer p to the left k nodes. If p is removed from the linked list, then p is set to 0, and Pr remain in the linked list of the left-most node.