[LeetCode]19 删除链表的倒数第N个节点

题目描述

给定一个链表，删除链表的倒数第 n 个节点，并且返回链表的头结点。

示例:

给定一个链表: 1->2->3->4->5, 和 n = 2.
当删除了倒数第二个节点后，链表变为 1->2->3->5.

代码

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# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def removeNthFromEnd(self, head, n):
        """
        :type head: ListNode
        :type n: int
        :rtype: ListNode
        """
        res = ListNode(0)
        res.next = head
        pre = end = res
        for i in range(n+1):
            pre = pre.next
        while pre:
            pre = pre.next
            end = end.next
        end.next = end.next.next
        return res.next