题目链接：
https://leetcode-cn.com/problems/rotate-list/comments/
解题思路：
先弄成环，然后断链接。
1 class Solution { 2 public ListNode rotateRight(ListNode head, int k) { 3 if(head == null) return null; 4 ListNode cur = head; 5 int n = 1; 6 while(cur.next != null){//得到链表的长度 7 n++; 8 cur = cur.next; 9 } 10 cur.next = head;//行成循环链表 11 int m = n - k % n; 12 for(int i = 0; i < m; i++){//到达新链表头节点的前一个节点 13 cur = cur.next; 14 } 15 ListNode newHead = cur.next; 16 cur.next = null; 17 return newHead; 18 } 19 }