https://leetcode.com/problems/rotate-list/ 除了AC以外，还实现了一些链表的方法，如fromArray， toString等
public class Main { public static void main(String[] args) { ListNode listNode = new Solution().rotateRight(ListNode.fromArray(new int[]{1, 2, 3, 4, 5}), 2); System.out.println(listNode); } } class ListNode { int val; ListNode next; ListNode(int x) { val = x; } static ListNode fromArray(int[] arr) { ListNode head = new ListNode(arr[0]); ListNode p = head; for (int i = 1; i < arr.length; i++) { p.next = new ListNode(arr[i]); p = p.next; } return head; } @Override public String toString() { ListNode p = this; String str = ""; while (p != null) { str += (p.val); if (p.next != null) str += ("->"); p = p.next; } return str; } } class Solution { int getLength(ListNode head) { int cnt = 0; while (head != null) { head = head.next; cnt++; } return cnt; } public ListNode rotateRight(ListNode head, int k) { if (head == null) return head; int length = getLength(head), i = 0; k = k % length; if (k == 0) return head; k = length - k; ListNode pre = head, p = head, end = head; while (i < k) { pre = p; p = p.next; end = p; i++; } while (end.next != null) end = end.next; end.next = head; pre.next = null; return p; } }