我试图通过数据结构和链表来巩固我的基础知识，但我一直面临这个错误

Question

代码如下：

class Node:
    def __init__(self, data, next):
        self.data = data
        self.next = None


class Linked List:
    def __init__(self, data):
       self.data = data
       self.head = None

    def print_list(self):
        cur_node = self.head
        
        while cur_node:
            print(cur_node.data)
            cur_node = cur_node.next

    def append(self, data):
        self.data = data
        new_node = Node(data, next)
    
        if self.head is None:
            self.head = new_node
            return
    
        last_node = self.head
        while last_node:
            last_node = last_node.next
            last_node.next = new_node

我这样称呼它：

lst=Linked List()
lst.append("A")
lst.append("B")
lst.print_list()

我得到的错误是：

C:\Users\vaish\PycharmProjects\hello\venv\Scripts\python.exe C:/Users/vaish/PycharmProjects/hello/hackerrank.py
Traceback (most recent call last):
  File "C:/Users/vaish/PycharmProjects/hello/hackerrank.py", line 202, in <module>
    llist=LinkedList()
TypeError: __init__() missing 1 required positional argument: 'data'

Process finished with exit code 1

有任何更正吗？

Answer 1

你的链表构造函数是一个参数化的 def init(self, data):

因此 python 期望在您使用此 lst=Linked List() 创建链表时的数据值。

只要在那里提供一些数据，它就会起作用。

例如。 lst=链表("A")

Answer 2

您的链表实现有一些错误。我已经评论了您需要更改的代码

class Node:
    def __init__(self, data): # do not pass next here
        self.data = data       
        self.next = None      # new node should have next=None by default


class Linked_List:
    def __init__(self):    # no need to pass data here, pass data in append function
       self.head = None    # self.head is our head of linked list

    def print_list(self):
        cur_node = self.head
        
        while cur_node:
            print(cur_node.data)
            cur_node = cur_node.next

    def append(self, data):
        #self.data = data        
        new_node = Node(data)     # data will be assigned to the newley created node automatically
    
        if self.head is None:
            self.head = new_node
            return
    
        last_node = self.head
        while last_node.next:     # you have get the last node 
            last_node = last_node.next
        last_node.next = new_node   # this should come outside of the while loop 
                                    #set next of last node as newly created node
lst=Linked_List()
lst.append("a")
lst.append("b")
lst.append("c")
lst.print_list()

我试图通过数据结构和链表来巩固我的基础知识，但我一直面临这个错误

I'm trying to make my basics strong with data structures and linked lists, I keep facing this error

data-structures

python-3.x

singly-linked-list