Given the head of a sorted linked list, delete all duplicates such that each element appears only once. Return the linked list sorted as well.
Input: head = [1,1,2]
Output: [1,2]
Input: head = [1,1,2,3,3]
Output: [1,2,3]
给定一个已排序的链表的头 head ， 删除所有重复的元素，使每个元素只出现一次 。返回 已排序的链表 。
class Solution:def deleteDuplicates(self, head: Optional[ListNode]) -> Optional[ListNode]:if head is None:return Nonecur = headwhile cur.next:if cur.next.val == cur.val:cur.next = cur.next.nextelse:cur = cur.nextreturn head
