题目

给你单链表的头节点 head ，请你反转链表，并返回反转后的链表。

示例 1：

输入：head = [1,2,3,4,5]
输出：[5,4,3,2,1]

解

class Solution {public ListNode reverseList(ListNode head) {if(head == null || head.next == null){return head;}ListNode pre = null;ListNode cur = head;ListNode next = null;while(cur != null){next = cur.next;cur.next = pre;pre = cur;cur = next;}return pre;}
}