LintCode 翻转链表

/**
* Definition for ListNode.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int val) {
*         this.val = val;
*         this.next = null;
*     }
* }
*/

public class Solution {
/*
* @param head: n
* @return: The new head of reversed linked list.
*/
public ListNode reverse(ListNode head) {
if (head==null){
return head;
}
ListNode p=head;
ListNode next=head.next;
ListNode pre=new ListNode(0);
pre.next=head;

while(p!=null){
next=p.next;
p.next=pre;
pre=p;
p=next;
}
head.next=null;
return pre;
}
}