#删除有序链表中的重复结点  
class Solution:
    def deleteDuplicates(self,head):
        if head==None or head.next==None:
            return head
        cur=head
        while cur.next!=None:
            if cur.val==cur.next.val:
                cur.next=cur.next.next
            else:
                cur=cur.next
        return head