# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
#
# 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
#
#
# @param pHead ListNode类
# @return ListNode类
#
class Solution:
def deleteDuplication(self, pHead: ListNode) -> ListNode:
# write code here
if not pHead or not pHead.next:
return pHead
head = ListNode
head.next = pHead
p = head.next
pre = head
flag = False
while(p.next):
if(p.next.val == p.val):
p = p.next
pre.next = p
flag = True
elif(p.next.val != p.val and flag):
p = p.next
pre.next = p
flag = False
else:
p = p.next
pre = pre.next
if flag:
pre.next = None
return head.next