Given a list, rotate the list to the right by k places, where k is non-negative.

 public class Solution {

     private int getLength(ListNode head) {

         int length = 0;

         while (head != null) {

             length ++;

             head = head.next;

         }

         return length;

     }

     public ListNode rotateRight(ListNode head, int n) {

         if (head == null) {

             return null;

         }

         int length = getLength(head);

         n = n % length;

         ListNode dummy = new ListNode(0);

         dummy.next = head;

         head = dummy;

         ListNode tail = dummy;

         for (int i = 0; i < n; i++) {

             head = head.next;

         }

         while (head.next != null) {

             tail = tail.next;

             head = head.next;

         }

         head.next = dummy.next;

         dummy.next = tail.next;

         tail.next = null;

         return dummy.next;

     }

 }

 class Solution {

 public:

     /**

      * @param head: the list

      * @param k: rotate to the right k places

      * @return: the list after rotation

      */

     ListNode *rotateRight(ListNode *head, int k) {

         if (head == NULL) {

             return head;

         }

         int len = ;

         for (ListNode *node = head; node != NULL; node = node->next) {

             len++;

         }

         k = k % len;

         if (k == ) {

             return head;

         }

         ListNode *fast = head;

         for (int i = ; i < k; i++) {

             fast = fast->next;

         }

         ListNode *slow = head;

         while (fast->next != NULL) {

             slow = slow->next;

             fast = fast->next;

         }

         fast->next = head;

         head = slow->next;

         slow->next = NULL;

         return head;

     }

 };