A linked list as a tuple Python

Question

A connected list is given, which is implemented as a tuple (a number, link to the following pair) of the form in which the values are already sorted:
x = (1, (3, (4, (7, (9, None)
It is necessary to implement a function that reverses the list:
example of a call:
reverse((1, (3, (6, (8, None)))))
Result:
(8, (6, (3, (1, None))))

This is what i’ve done, i know it’s incorrect cause first element would be doubled then

def reverse(linked_list: tuple):
    last_pair = (linked_list[0], None)
    while linked_list[1]:
        new_list = (linked_list[0], last_pair)
        return new_list
        return reverse(linked_list[1])

This is the result:
(1, (1, None))

I have no idea how to do it in correct way, there is nothing about linked lists as tuples on the internet

Asked By: Nastya___

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Source

Answer 1

The implementation in the question does not evaluate all parts of the argument passed to reverse().

Here’s one way to achieve your objective:

def reverse(t):
    result = None
    while True:
        a, b = t
        result = a, result
        if (t := b) is None:
            break
    return result
    
print(reverse((1, (3, (6, (8, None))))))

Output:

(8, (6, (3, (1, None))))

Answered By: Fred

Answer 2

If you supply an additional argument for "reverse" sequence you can also succeed with recursive function:

def reverse(linked_t: tuple, rev_seq=None):
    while linked_t[1] is not None:
        rev_seq = (linked_t[0], rev_seq)
        return reverse(linked_t[1], rev_seq)
    else:
        return linked_t[0], rev_seq


print(reverse((1, (3, (6, (8, None))))))

(8, (6, (3, (1, None))))

Answered By: RomanPerekhrest

A linked list as a tuple Python

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