题解 | #删除有序链表中重复的元素-II#

# 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 head ListNode类 
# @return ListNode类
#
class Solution:
    def deleteDuplicates(self , head: ListNode) -> ListNode:
        # write code here
        dummy = pre = ListNode(-1)
        while head and head.next:
            if head.val == head.next.val:
                temp = head.val
                while head and head.val == temp:
                    head = head.next
                continue
            else:
                pre.next = head
                pre = pre.next
                head = head.next
        pre.next = head
        return dummy.next