【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.

start with an example.

Given [0,1,2], rotate 1 steps to the right
-> [2,0,1].

Given [0,1,2], rotate 2 steps to the right
-> [1,2,0].

Given [0,1,2], rotate 3 steps to the right
-> [0,1,2].

Given [0,1,2], rotate 4 steps to the right
-> [2,0,1].

So, no matter how big K, the number of steps is, the result is always the
same as rotating K % n steps to the right.

public class Solution {

    public ListNode rotateRight(ListNode head, int n) {

        if(head==null||head.next==null||n==0)

            return head;

        int len = 0;

        ListNode root = head;

        while(root!=null){

            root=root.next;

            len++;

        }

ListNode fast = head;

        ListNode slow = head;

        int i=n%len;

        if(i==0)

            return head;

        while(i>0&&fast!=null){

            fast=fast.next;

            i--;

        }
while(fast.next!=null){

            slow=slow.next;

            fast=fast.next;

        }
ListNode tem = slow.next;

        fast.next=head;

        slow.next=null;

        return tem;
}

}

【LeetCode】Rotate List