[leetcode]61. Rotate List

题目链接：https://leetcode.com/problems/rotate-list/#/description

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

.

class Solution {
public:
ListNode* rotateRight(ListNode* head, int k) {
if(!head)
return head;

int len=1;
ListNode* newH,*tail;
newH=tail=head;
while(tail->next)
{
tail=tail->next;
len++;
}
tail->next=head;
if(k%=len)
{
for(auto i=0;i<len-k;i++)
tail=tail->next;
}
newH=tail->next;
tail->next=NULL;
return newH;
}
};