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

.

Runtime: 12ms.

/**
* 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 || !head->next) return head;

// first find the (n - k % n)th element
ListNode* move = head;
int count = 1;
while(move->next) {
count++;
move = move->next;
}
ListNode* endNode = move;

k %= count;
move = head;
int index = 0;
while(index++ < k)
move = move->next;

ListNode* current = head;
while(move->next) {
move = move->next;
current = current->next;
}
endNode->next = head;
head = current->next;
current->next = NULL;

return head;
}
};