制作链表时对节点感到困惑

Question

I'm trying to make a linked list in python without using classes. But I'm a little confused.

Here's an example of what I'm trying to achieve: head = [None,None] n = integer and the function is getting called from a loop

def append(head, n):
    node = head
    while node[1] != None: # Find last node
        node = node[1]
    node[1] = [n,None]  # Attach new node

Basically using a node that holds a value and points to next. Now I'm trying to do something similar with my program, the main difference being that the example gets the head which contains [None,None] and in my program I get 10 empty lists instead. This is what I got:

def add(word_set,word):
    node = word_set
    node[-1] = [word,None]
    while node[1] != None:
        node = node[1]
        node[1] = [word,None]

getting called by this from main:

names = ["Ella", "Owen", "Fred", "Zoe", "Adam", "Ceve", "Adam", "Ceve", "Jonas", "Ola", "Morgan", "Fredrik", "Simon", "Albin", "Måns", "Amer", "David"]

word_set = ws.new_empty_set()
for s in names:
    ws.add(word_set,s)

I dont quite know how to replicate the example function with my code. I always get index out of range when I try. Also I dont want to make any changes to main.py

Answer 1

Some issues:

• Assuming that new_empty_set returns an empty list, in add the assignment node[-1] = will produce the error that you mention. You should verify first whether the list is empty and deal with that boundary case separately.

• The last line of add should not be part of the loop. It should be executed after the loop finishes.

• Less important, but using the name "set" is confusing, as set is a native type that is not a list, but a hash set. So I would use the term "linked_list" instead

Corrected code:

# assuming this definition, but don't call it *set
#   but *linked_list:
def new_empty_linked_list():
    return []

def add(word_linked_list, word):   # change of name
    node = word_linked_list
    if not node:  # the list is empty
        node.extend([word, None])
    else:
        while node[1] != None:
            node = node[1]
        node[1] = [word, None]  # outside of loop

names = ["Ella", "Owen", "Fred", "Zoe", "Adam", "Ceve", "Adam", "Ceve", "Jonas", "Ola", "Morgan", "Fredrik", "Simon", "Albin", "Måns", "Amer", "David"]

word_linked_list = new_empty_linked_list()
for s in names:
    add(word_linked_list, s)

print(word_linked_list)

There are some duplicate names in your input. You haven't mentioned what should happen with those, and your add function doesn't deal with them differently. But if the list should not store duplicates, then you should add some condition in your loop:

def add(word_linked_list, word):
    node = word_linked_list
    if not node:
        node.extend([word, None])
    else:
        # add condition to spot duplicate value
        while node[0] != word and node[1] != None:
            node = node[1]
        if node[0] != word:  # only add when unique
            node[1] = [word, None]