题解 | #反转链表#新思路

import java.util.*;

public class Solution {
    public ListNode ReverseList (ListNode head) {
        // write code here
        ListNode res = new ListNode(-1);//头结点前面
        res.next = head;
        ListNode pre = res;
        if(head == null){
            return head;
        }

        // ListNode first = head;

        while(head.next != null){
            //每次都把后面的节点插入到反转部分的最前面去
            ListNode temp = head.next;
            head.next = temp.next; //first向后移动一个结点
            temp.next = pre.next; // 连接前面的结点
            pre.next = temp;
        }
        return res.next;
    }
}