ListNode* deleteDuplication(ListNode* pHead)
{
if(pHead==nullptr)
return nullptr;
auto p=pHead,pn=p->next,pnn=p;
while(p!=nullptr&&pn!=nullptr)
{
pnn=pn->next;
if((p->val)==(pn->val))
{
p->next=pnn;
delete pn;
pn=pnn;
}
else
{
p=pn;
pn=pnn;
}
}
return pHead;
}