/*
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
/
class Solution {
public ListNode deleteDuplication(ListNode head) {
if(head==null)
return null;
ListNode dummy=new ListNode(-1);
dummy.next=head;
ListNode node=head;
ListNode pre=dummy;
while(node!=null&&node.next!=null){
if(node.val==node.next.val){
int val2=node.val;
while(node!=null&&node.val==val2)
node=node.next;
pre.next=node;
}
else{
pre=node;
node=node.next;
}
}
return dummy.next;
}
}