Given a linked list, rotate the list to the right by k places, where k is non-negative.
Example 1:
Input: 1->2->3->4->5->NULL, k = 2
Output: 4->5->1->2->3->NULL
Explanation:
rotate 1 steps to the right: 5->1->2->3->4->NULL
rotate 2 steps to the right: 4->5->1->2->3->NULL
Example 2:
Input: 0->1->2->NULL, k = 4
Output: 2->0->1->NULL
Explanation:
rotate 1 steps to the right: 2->0->1->NULL
rotate 2 steps to the right: 1->2->0->NULL
rotate 3 steps to the right: 0->1->2->NULL
rotate 4 steps to the right: 2->0->1->NULL
来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/rotate-list
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/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode rotateRight(ListNode head, int k) {
if(head==null || head.next==null || k==0) return head;
ListNode old = head;
int n = 0;
while(old.next!=null){
old = old.next;
++n;
}
old.next = head;
k %= (n+1);
ListNode newL = old;
for(int i=0; i<n-k+1; ++i){
newL = newL.next;
}
ListNode newHead = newL.next;
newL.next = null;
return newHead;
}
}