Rotate List

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

For example:
Given 1->2->3->4->5->NULL and k = 2,
return 4->5->1->2->3->NULL.

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    ListNode* rotateRight(ListNode* head, int k) {        if(!head || k == 0){            return head;        }        ListNode * cur = head;        int len = 1;        while(cur->next != NULL){            len ++;            cur = cur->next;        }        cur->next = head;        int offset = len - k % len;        cur = head;        while(offset > 1){            cur = cur->next;            offset--;        }        head = cur->next;        cur->next = NULL;        return head;    }};