js怎么做网站客服聊天专业搜索引擎seo合作

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题目

给你一个链表，删除链表的倒数第 n 个结点，并且返回链表的头结点。

示例 1：

输入：head = [1,2,3,4,5], n = 2
输出：[1,2,3,5]

示例 2：

输入：head = [1], n = 1
输出：[]

示例 3：

输入：head = [1,2], n = 1
输出：[1]

提示：

• 链表中结点的数目为 sz
• 1 <= sz <= 30
• 0 <= Node.val <= 100
• 1 <= n <= sz

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答案

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution(object):def removeNthFromEnd(self, head, n):""":type head: ListNode:type n: int:rtype: ListNode"""dummy = ListNode(0)dummy.next = headarr = [dummy]while head:arr.append(head)head = head.nextfor _ in range(n + 1):pre = arr.pop()pre.next = pre.next.nextreturn dummy.next

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运行结果