给定一个单链表，然后对它反序。

ListNode类

 

public class ListNode {int val;ListNode next;ListNode(int x){val=x;next=null;}ListNode(){}ListNode(int x,ListNode node){val=x;next=node;}public void setVal(int val){this.val=val;}public int getVal(){return val;}public void setListNode(ListNode next){this.next=next;}public ListNode getListNode(){return next;}//单链表反序public ListNode reverse(ListNode head){ListNode pre=null;ListNode next=null;while(head!=null){next=head.next;head.next=pre;pre=head;head=next;}return pre;}}

给定一个双链表反序