82. 删除排序链表中的重复元素 II

https://leetcode-cn.com/problems/remove-duplicates-from-sorted-list-ii/

给定一个排序链表，删除所有含有重复数字的节点，只保留原始链表中 没有重复出现 的数字。

示例 1:

输入: 1->2->3->3->4->4->5
输出: 1->2->5
示例 2:

输入: 1->1->1->2->3
输出: 2->3

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        dummy = ListNode(-1)
        dummy.next = head
        cur = dummy
        while cur.next and cur.next.next:
            if cur.next.val == cur.next.next.val:
                tmp = cur.next
                while tmp and tmp.next and tmp.val == tmp.next.val:
                    tmp = tmp.next
                cur.next = tmp.next
            else:
                cur = cur.next
        return dummy.next