题解 | #删除有序链表中重复的元素-II#

class Solution:
    def deleteDuplicates(self, head: ListNode) -> ListNode:
        # if empty, return None
        if not head:
            return None

        # initiate the res for return and cur for checking
        res = cur = ListNode(0)
        cur.next = head

        while cur.next and cur.next.next:
            # if next 2 nodes have the same val, record this val into tmp
            if cur.next.val == cur.next.next.val:
                tmp = cur.next.val
                # keep moving the pointer until the val get rid of this val
                while cur.next and cur.next.val == tmp:
                    cur.next = cur.next.next
            # if next 2 val is not the same, move to the first one
            else:
                cur = cur.next
        return res.next