61. 旋转链表

力扣https://leetcode-cn.com/problems/rotate-list/难度中等646

给你一个链表的头节点 head ，旋转链表，将链表每个节点向右移动 k 个位置。

示例 1：

输入：head = [1,2,3,4,5], k = 2
输出：[4,5,1,2,3]

示例 2：

输入：head = [0,1,2], k = 4
输出：[2,0,1]

提示：

• 链表中节点的数目在范围 [0, 500] 内
• -100 <= Node.val <= 100
• 0 <= k <= 2 * 109

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode rotateRight(ListNode head, int k) {
        if(head==null || k<1 ) return head;
        ListNode node = head;
        ListNode temp = head;
        while(k>0)
        {
            node = node.next;
            if(node==null && k!=0)
                node = head;
            k--;
        }
        while(node!=null && node.next!=null)
        {
            node = node.next;
            temp = temp.next;
        }
        if(node!=null)
        {
            node.next = head;
            head = temp.next;
            temp.next = null;
        }
        return head;
    }
}