【leetcode】Rotate List

class Solution {
public:
ListNode* rotateRight(ListNode* head, int k) {
if(head == NULL) return head;
ListNode *p = head;
int len = 0;
while(p->next){
p = p->next;
len++;
}
len++;

p->next = head;  //link head and tail

k %= len;
int temp = len - k;
while(temp > 0){
p = p->next;
temp--;
}
head = p->next;
p->next = NULL;

return head;

}
};