[leetcode] Rotate List

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/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ public class Solution { public ListNode rotateRight(ListNode head, int k) { if (head == null || head.next == null) return head; int length = 0; ListNode current = head; ListNode previous = null; while (current != null){ length++; previous = current; current = current.next; } k = k % length; if (k == 0) return head; ListNode fast = head; for (int i = 0; i < k; i++){ fast = fast.next; } ListNode newEnd = null; ListNode newStart = head; while (fast != null){ newEnd = newStart; newStart = newStart.next; fast = fast.next; } previous.next = head; newEnd.next = null; return newStart; } }