82. Remove Duplicates from Sorted List II
Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.
Return the linked list sorted as well.
递归，需要分 head.val == next.val 和 head.val != next.val 两种情况。
# Definition for singly-linked list.
class ListNode:
def __init__(self, x):
self.val = x
self.next = None
class Solution:
def deleteDuplicates(self, head: ListNode) -> 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)
head.next = self.deleteDuplicates(head.next)
return head