删除链表中倒数第N和节点

一、问题描述

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]

from heapq import heapify, heappop, heappush
from math import inf
from typing import List
from typing import Optional
from clang.cindex import Config
class ListNode:
     def __init__(self, val=0, next=None):
         self.val = val
         self.next = next

head = [1,2,3,4,5]

def creat_tail(li):
    head = ListNode(li[0])
    tail = head
    for element in li[1:]:
        node = ListNode(element)
        tail.next = node
        tail = node
    return head

head1 = creat_tail(head)

class Solution:
    def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
        def getlenght(head: ListNode) -> int:
            length = 0
            while head:
                length += 1
                head = head.next
            return length
        cur = dummy = ListNode(0,head)
        length = getlenght(head)

        for i in range(1, length - n + 1):
            cur = cur.next
        cur.next = cur.next.next
        return dummy.next



def printlink(li):
    while li:
        print(li.val,end=',')
        li = li.next
#printlink(head1)


S= Solution()
printlink(S.removeNthFromEnd(head1,2))

二、结果展示

1,2,3,5,