从列表末尾删除第N个节点(Leetcode)？- Python

class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

def removeNthFromEnd(head, n):
    dummy = ListNode(0)  # 创建一个虚拟头节点
    dummy.next = head
    first = dummy
    second = dummy

    # 先将第一个指针移动n步
    for i in range(n + 1):
        first = first.next

    # 同时移动两个指针，直到第一个指针到达末尾
    while first is not None:
        first = first.next
        second = second.next

    # 删除倒数第N个节点
    second.next = second.next.next

    return dummy.next