在一个排序的链表中，存在重复的结点，请删除该链表中重复的结点，重复的结点不保留，返回链表头指针。

    public ListNode deleteDuplication(ListNode pHead) {
        ListNode cur = this.head;
        ListNode newHead = new ListNode(-1);
        ListNode tmp = newHead;
        while (cur != null){
            if (cur.next != null && cur.val == cur.next.val){
                while (cur.next != null && cur.val == cur.next.val){
                    cur = cur.next;
                }
                cur = cur.next;
            }else {
                tmp.next = cur;
                tmp = tmp.next;
                cur = cur.next;
            }
        }
        tmp.next = null;
        return newHead.next;
    }