python LeetCode brush test record 83

topic

Given the head of a sorted linked list, remove all duplicate elements so that each element appears only once. Returns a sorted linked list.

code

class Solution:
    def deleteDuplicates(self, head: Optional[ListNode]) -> Optional[ListNode]:
        if head:# 判断非空链表
            current = head # 定义一个指针遍历链表
            while current.next:
                if current.val == current.next.val:
                # 指针不动，只改变链表的部分指向
                    if current.next.next: # 当前与下一个相等且下下个不为空，则指向下下个
                        current.next = current.next.next
                    else: # 当前与下一个相等，且没有下下个，则将当前指向空
                        current.next = None
                else: # 如果当前与下一个不等，则将指针往后移
                    current = current.next
            return head