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