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
        h = head
        l2 = []
        dup = set()
        last = None
        while h:
            v = h.val
            if v == last:
                dup.add(v)
            l2.append(h.val)
            last = v
            h = h.next
        l=[]
        for i in l2:
            if i not in dup:
                l.append(i)

        dummy = ListNode(0)
        current = dummy
        for i in l:
            current.next = ListNode(i)
            current = current.next
        return dummy.next