public class Solution {
public ListNode deleteDuplication(ListNode pHead){
if(pHead==null||pHead.next==null)return pHead;
ListNode p = pHead.next;
ListNode chongfu = pHead;
boolean flag=true;
ListNode res = new ListNode(0);
ListNode pans = res;
while(p!=null){
if(p.val!=chongfu.val&&flag){
res.next = chongfu;
res=res.next;
chongfu = p;
}
else if(p.val==chongfu.val){
flag=false;
}else if(p.val!=chongfu.val&&!flag){
chongfu = p;
flag=true;
}
p = p.next;
}
if(flag){
res.next = chongfu;
res=res.next;
}
res.next = null;
return pans.next;
}
}