题解 | #反转链表#

头插法倒序

public class Solution {
    public ListNode ReverseList(ListNode head) {
        if(head==null||head.next==null)return head;
        ListNode newhead=new ListNode(-1);
        ListNode after=new ListNode(-1);
        while(head!=null){
            after=head.next;//原来链表后续节点

            ListNode node=newhead.next;//新链表头插
            newhead.next=head;//头插
            head.next=node;//头插

            head=after;          
        }
        return newhead.next;
    }
}