python实现leetcode之82. 删除排序链表中的重复元

解题思路

每个节点有三种情况
1.前面有重复的节点
2.后面有重复的节点
3.前后都没有重复的节点

只保留第三种！

82. 删除排序链表中的重复元素 II

代码

# 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:
        ans = tail = ListNode(0)
        dup_val = None
        while head:
            if head.val == dup_val:  # 前面有重复
                head = head.next
                continue
            elif head.next and head.val == head.next.val:  # 后面有重复
                dup_val = head.val
                head = head.next
                continue
            else:  # 前后都没有重复
                tmp = head.next
                # 插入返回值尾部
                tail.next = head
                tail = head
                head = tmp
        tail.next = None
        return ans.next