LeetCode_Rotate List

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.

　　巨没劲的一道题，当k>length 时，我以为origin list 不动就行，结果好些case过不了，看了别人的代码才知道要 k%= length 真心想不通为什么，也懒得弄这种恶心的东西。面试遇到这种题目直接问面试官这种奇葩情况怎么处理就行。

/**
 * 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) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(head == NULL || k == 0) return head;
		ListNode *p, *q;
		p = head;q= p;
		while(q &&--k){
			q = q->next;
		}
		if(k >0 || NULL == q) return head;
		ListNode *pre = NULL;
 
		while(q->next){
			pre = p;
			p = p->next;
			q = q->next;
		}
		q ->next = head;
		head  = p;
		pre ->next = NULL;
		return head;
 
    }
};