function deleteDuplication(pHead)
{
    // write code here
    var newHead = new ListNode('head');
    newHead.next = pHead;
    var pHead = newHead;
    var qHead = pHead.next;
    while(qHead) {
        while((qHead.next!=null) && (qHead.val == qHead.next.val)) {
            qHead = qHead.next;
        }
        //没移动
        if(pHead.next == qHead) {
            pHead = qHead;
            qHead = qHead.next;
             
        }
        //移动了
        else {
            qHead = qHead.next;
            pHead.next = qHead;
             
        }
         
    }
    return newHead.next;
     
}