力扣：82. 删除排序链表中的重复元素 II（Python3）

题目：

给定一个已排序的链表的头 head ， 删除原始链表中所有重复数字的节点，只留下不同的数字 。返回 已排序的链表 。

代码：

# Definition for singly-linked list.

# class ListNode:

#     def __init__(self, val=0, next=None):

#         self.val = val

#         self.next = next

class Solution:

    def deleteDuplicates(self, head: Optional[ListNode]) -> Optional[ListNode]:

        list1 = []

        while head:

            list1.append(head.val)

            head = head.next

        list1 = [k for k, v in Counter(list1).items() if v == 1]

        head = point = ListNode()

        for num in list1:

            node = ListNode(num)

            point.next = node

            point = point.next

        return head.next