JZ56 删除链表中重复的结点

public class Solution {
    public ListNode deleteDuplication(ListNode pHead){
        if(pHead==null) return null;
        ListNode prev=new ListNode(pHead.val-1);
        prev.next=pHead;
        ListNode l1=prev, l2=pHead;
        while(l2.next!=null){
            if(l2.val==l2.next.val){
                ListNode l3=l2.next;
                while(l3!=null&&l2.val==l3.val){
                    l2=l2.next; l3=l3.next;
                }
                l1.next=l3;
                if(l3==null){
                    return prev.next;
                }else{
                    l2=l1.next;
                    continue;
                }
            }
            l1=l1.next; l2=l2.next;
        }
        return prev.next;
    }
}