1、前言

2、思路

双指针

3、代码

class Solution {
    public ListNode reverseList(ListNode head) {
        if(head == null){
            return null;
        }
        ListNode dummy = new ListNode(-1);
        while (head != null){
            ListNode next = dummy.next;
            ListNode temp = head.next;
            dummy.next = head;
            head.next = next;
            head = temp;
        }
        return dummy.next;
    }
}