[LeetCode] 61. Rotate List

ProblemGiven a linked list, rotate the list to the right by k places, where k is non-negative.Example 1:Input: 1->2->3->4->5->NULL, k = 2Output: 4->5->1->2->3->NULLExplanation:rotate 1 steps to the right: 5->1->2->3->4->NULLrotate 2 steps to the right: 4->5->1->2->3->NULLExample 2:Input: 0->1->2->NULL, k = 4Output: 2->0->1->NULLExplanation:rotate 1 steps to the right: 2->0->1->NULLrotate 2 steps to the right: 1->2->0->NULLrotate 3 steps to the right: 0->1->2->NULLrotate 4 steps to the right: 2->0->1->NULLSolutionclass Solution { public ListNode rotateRight(ListNode head, int k) { if (head == null || head.next == null || k == 0) return head; ListNode dummy = new ListNode(0); dummy.next = head; ListNode fast = dummy, slow = dummy; int n = 0; while (fast.next != null) { fast = fast.next; n++; } k = n-k%n; while (k > 0) { slow = slow.next; k–; } fast.next = dummy.next; dummy.next = slow.next; slow.next = null; return dummy.next; }}