LeetCode刷题（C++）——Rotate List（Medium）

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.

/** * 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 == NULL)return NULL;int count = 0;ListNode* p = head;while (p != NULL){count++;p = p->next;}k = k%count;if (k == 0)return head;ListNode* fast = head;ListNode* slow = head;for (int i = 0; i < k;i++)fast = fast->next;while (fast->next != NULL){fast = fast->next;slow = slow->next;}if (slow->next == NULL)return head;else{p = slow->next;fast->next = head;slow->next = NULL;return p;}    }};