如何在Python中将双重链接列表实现到我的树形结构中？

Question

So I'm trying to represent an XML file using python. I already managed to do that. But each child node in my tree has to be doubly linked and I don't know how to do that. I've found a few examples of code online but they all use classes and the professor doesn't want us using classes. Here's my code:

from xml.etree.ElementTree import ElementTree
from xml.etree.ElementTree import Element
import xml.etree.ElementTree as etree


def create_tree(): #This function creates the root element of my tree
    n = input("Enter your root Element: ")
    root = Element(n)
    tree = ElementTree(root)
    print(etree.tostring(root))
    return root

def add_child():
    root = create_tree()
    new = True
    while new == True:
        ask = input("If you wish to add a new child type 'yes', else type something else: ")
        if ask == 'yes':
            n = input("Enter the name of the node: ") #This block of code creates a child and appends it to the root element
            node = Element(n)
            root.append(node)
            print(etree.tostring(root))
        else:
            break
    return etree.tostring(root)
add_child()

For those of you wondering, the purpose of this project is to create a rooted tree with unbounded branching. I hope that once I can implement the doubly linked list I will be able to add a child node within a child node.

Answer 1

You should be able to implement a linked list using lists. You can define each element as a list with the element itself, the item before it, and the item after it. If the list contains the previous node, the next node, and the element itself, respectively, and the head is stored in head , the syntax to append newElement to the beginning of the list would be as follows:

newNode = [None,head,newElement]
head[0] = newNode
head = newNode