【Rotate List】cpp

/**
 * 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;
        ListNode *p = head;
        int len = 1;
        for (;p->next;++len,p=p->next){}
        ListNode *end = p;
        k = k % len;
        p = head;
        for (size_t i = 0; i < len-k-1; ++i)
        {
            p = p->next;
        }
        end->next = head;
        head = p->next;
        p->next = NULL;
        return head;
    }
};