#include <cstddef>

struct ListNode {

int val;

ListNode *next;

ListNode(int x) : val(x), next(NULL) {}

};

class Solution {

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

if (head == NULL || k == 0) return head;

ListNode *slow = head, *fast = head;

while (k--) {

if (fast == NULL) fast = head;

fast = fast->next;

}

if (fast == NULL) return head;

while (fast->next) {

fast = fast->next;

slow = slow->next;

}

ListNode *new_head = slow->next;

slow->next = NULL;

fast->next = head;

return new_head;

}

};