这是一个非常简单的程序,在链接列表的末尾添加一个节点。我不知道我犯了什么错误。它与hackerRank的输出有关,或者我的代码中有错误。我正在尝试实现 Python2
class Node(object):
def __init__(self, data=None, next_node=None):
self.data = data
self.next = next_node
def Insert(head, data):
if (head.head == None):
head.head = Node(data)
else:
current = head.head
while (current.next != None) and (current.data == data):
current = current.next
current.next = Node(data)
这是问题的链接。https://www.hackerrank.com/challenges/insert-a-node-at-the-tail-of-a-linked-list
如果一定要在链接列表末尾添加那么就不需要测试current.data == data
了,下面的代码应该足够了——
def Insert(head, data):
if (head == None):
head = Node(data)
else:
current = head
while (current.next != None):
current = current.next
current.next = Node(data)
return head
另请注意,Python 不需要在 if 和 while 之后使用 ()
。
您的代码有几个问题:
-
head
要么是None
,要么是Node
的实例。也没有head
属性,所以head.head
没有意义。 -
None
是单例,因此请测试something is None
而不是something == None
,something is not None
而不是something != None
。 - 您应该返回修改列表的头部。您的函数不返回任何内容。
这个将通过 python3 的 HackerRank 解释器运行
#print ('This is start of the function')
node = SinglyLinkedListNode(data)
if (head == None):
head = node
else:
current = head
while (current.next != None):
current = current.next
current.next = node
return head
答案 -
#!/bin/python3
import math
import os
import random
import re
import sys
class SinglyLinkedListNode:
def __init__(self, node_data):
self.data = node_data
self.next = None
class SinglyLinkedList:
def __init__(self):
self.head = None
def print_singly_linked_list(node, sep, fptr):
while node:
fptr.write(str(node.data))
node = node.next
if node:
fptr.write(sep)
def insertNodeAtTail(head, data):
item = SinglyLinkedListNode(data)
if head is None:
head = item
else:
n = head
while(n.next):
n = n.next
n.next = item
return head
节点类:
类节点(对象): def init(self, item): 自我数据 = 项目 self.next = 无
def getdata(self):
return self.data
def setdata(self, item):
self.data = item
def getnext(self):
return self.next
def setnext(self, item):
self.next = item
最后插入的方法是
def insert(head, item):
newNode = Node(item)
newNode.setdata(item)
current = head
while current.getnext() != None:
current = current.getnext()
current.setnext(newNode)
用于单独的递归版本:
def getTail(node):
if node.next == None:
return node
return getTail(node.next)
def Insert(head, data):
if head == None:
return Node(data)
tail = getTail(head)
tail.next = Node(data)
return head
class SinglyLinkedListNode:
def __init__(self, node_data):
self.data = node_data
self.next = None
class SinglyLinkedList:
def __init__(self):
self.head = None
# Implementation
def insertNodeAtTail(head, data):
if head == None:
head = SinglyLinkedListNode(data)
else:
current = head
while current.next != None:
current = current.next
current.next = SinglyLinkedListNode(data)
return head
所以我只是在Hackerrank中实现了整个问题并通过了所有测试用例检查,我想这是解决方案...只有一个小问题是我用 Java 完成了它......但我会尽力解释它...
- 首先,我为尾部的每个添加创建了一个节点。
- 然后,我通过在 main 方法中调用 append 函数来添加它们,以限制 for 循环。
- 每次调用时,它都会将输入整数数据添加到节点,并将其附加到列表中的前一个节点。
- 最后打印出来。
- 请阅读代码,我已经注释掉了解释它们作用的行......别担心,我试图让 python 学习者尽可能简单。
对不起,没看到这个问题是6年前发布的...好吧,我只想把这个答案贴在这里,这样它可能会帮助另一个有需要的人。
祝你好运,继续学习...
import java.io.*;
import java.util.*;
public class Solution {
// class Solution is what should be called as the LINKEDLIST class but its ok
Node head; // declaring a head for the LL
class Node { // Node class
int data; // the .data variable
Node ref; // .ref aka .next
Node(int data) { // constructor for initializing the values
this.data = data;
this.ref = null;
}
}
public void append(int data) { // i call 'to join at the end' as append
Node newnode = new Node(data); // new node creation
if (head == null) { // checking is head is null aka None in Py
head = newnode;
return;
}
Node curr = head; // assigning head to a curr node ready for traversal
while (curr.ref != null) { // traversal begins
curr = curr.ref;
} // traversal ends
curr.ref = newnode; // this is the last node where the join happens
}
public void p() { // i name printing function as p()
if (head == null) { // if head is null then print empty
System.out.println("Empty");
return;
}
Node curr = head; // same thing - traversal begins here
while (curr != null) {
System.out.println(curr.data);
curr = curr.ref;
} // by now all data values have been printed out already
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in); // scanner class for input
Solution l = new Solution(); // object creating for LL as Solution class name
int numberOfNodes = sc.nextInt(); // input for number of NODEs in LL
for (int i = 0; i < numberOfNodes; i++) { // loop for .data values
int data = sc.nextInt();
l.append(data); // function append call for each (i)
}
l.p(); // finally print func call to display output LL
}
}