Leetcode 82. 删除排序链表中的重复元素 II(Python3)

82. 删除排序链表中的重复元素 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:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        dummy = ListNode(None)
        dummy.next = head
        res = dummy
        while dummy.next:
            l = dummy.next
            r = l
            while r.next and r.next.val == l.val:
                r = r.next
            if l == r:
                dummy = dummy.next
            else:
                dummy.next = r.next
        return res.next

---

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

class Solution:
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        if not head or not head.next:
            return head
        if head.val == head.next.val:
            while head.next and head.val == head.next.val:
                head = head.next
            return self.deleteDuplicates(head.next)
        else:
            head.next = self.deleteDuplicates(head.next)
            return head