public class Solution {
    public ListNode ReverseList(ListNode head) {
        if(head == null || head.next == null)//考虑特殊情况
           return head;
        
        ListNode pre = null; //三个指针推动
        ListNode next = null;
       

        while(head!=null)

{next=head.next;

head.next = pre;

pre = head;

head=next;

}

return pre;

 

 

 

 

 

 

 

 

 

newhead=head.next;
        tem = newhead.next;
        head.next = null;
       
        while(newhead!=null){
        newhead.next = head;
        head = newhead;
        newhead = tem;
        if(newhead!=null)
            tem = newhead.next;
        }
       
        return head;
    }
   
}