旋转链表

/*
 * @lc app=leetcode.cn id=61 lang=cpp
 *
 * [61] 旋转链表
 */

// @lc code=start
/**
 * 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 || k == 0)
        {
            return head;
        }

        ListNode *p = head;
        ListNode *q = head;
        // 先求出链表总个数
        int number = 0;
        for (ListNode *k = head; k != nullptr; k = k->next)
        {
            number++;
        }

        k = k % number;
        for (int i = 0; i < k; i++)
        {
            p = p->next;
        }
        while (p->next != nullptr)
        {
            q = q->next;
            p = p->next;
        }
        p->next = head;
        head = q->next;
        q->next = nullptr;
        return head;
    }
};
// @lc code=end