🔒 Recursion search algorithm error

[finite lotus]

class Algorithms:
    def __init__(self, list) -> None:
        self.list = list
    
    def recursion_search(listn, start, end, index):
        if (end < start):
            print('wtf..')
            return ValueError('End is less than 0')
        else:
            middle_value = start + ((end - start) // 2)
            if listn[middle_value] < index: # The line that causes the problem
                return Algorithms.recursion_search(listn, middle_value+1, end, index)
            elif listn[middle_value] > index:
                return Algorithms.recursion_search(listn, start, middle_value-1, index)

When I run the code above I get this error
TypeError: 'LinkedList' object is not subscriptable

I don't know what that means please help

[clear swallow]

@finite lotus

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[finite lotus]

How do I add Syntax Highlighting?

Line 11 is what causing the issue.

listn is the list I'm trying to iterate over

[tranquil thicket]

But what did you inputted in?

[finite lotus]

A linked list

With a head node and more

[tranquil thicket]

And what is the linked list?

It's more like the issue with the linked list instead of the algorithm lul

[finite lotus]

Hold on this one is blurry

[tranquil thicket]

Tell me, how would the linkedlist could possibly do list[index]

Cuz I don't see where you implemented it

[finite lotus]

I don't know

[tranquil thicket]

Also you cannot use binary search either since the data is not ordered

[finite lotus]

I don't understand

[tranquil thicket]

And also if you are searching for index(which is in ordered), why do you need value of the list at the location

[tranquil thicket]

You have to show your implementation of linkedlist

[finite lotus]

I'm trying to get a specific value

[tranquil thicket]

And how have you implemented __getitem__ that allow you to use index

[tranquil thicket]

Since linkedlist is just a object instead of a actual list

[finite lotus]

Oh

Ok....

[finite lotus]

How do I do it?

[tranquil thicket]

You need to learn

Let me find docs for you

https://docs.python.org/3/reference/datamodel.html#special-method-names

Also you have to fully describe what the algorithm suppose to do, I suspect there is a large logical error

In one of the 2 way

[finite lotus]

It's a recursion algorithms

It's supposed to get an item in the list

A specific item

[tranquil thicket]

In what condition

[finite lotus]

Using the index of that item

[tranquil thicket]

Then why don't you just check every head and count the index

Why do you need a middle_value

[finite lotus]

I'm trying to apply an algorithm

[tranquil thicket]

But what the reason of using this algorithm

[finite lotus]

I'm making a library

[finite lotus]

Look at the imports

[tranquil thicket]

I mean, why do you need this algorithm, why logically this algorithm is better then just checking it one by one

[finite lotus]

I will code more algorithms, this is just the one I'm starting with

[tranquil thicket]

...I literally don't see any advantage and I see a logical issue

On the algorithm

[finite lotus]

I'm learning data structures and algorithms

[tranquil thicket]

I can see it's very similar to binary search

But binary search is suppose to find a value if it's exist on the list

[finite lotus]

Binary search by recursion

[tranquil thicket]

And binary search value must be ordered

[finite lotus]

How do I make it ordered??

[tranquil thicket]

Either order it(which no reason since you are making linkedlist) or don't use binary search

[finite lotus]

I'm so confused.

[tranquil thicket]

And in binary search, you need to give a value and it search for a value

[tranquil thicket]

Since you didn't learn binary search properly from what I see

[finite lotus]

I am making an algorithm so I can sort through the linked list?

[finite lotus]

What's wrong with this??

[tranquil thicket]

Where

And also binary search takes in a value, not a index

[finite lotus]

They are both in different files because I like to be organized.

I will send screenshots

[tranquil thicket]

(Also it's not logically reasonable to sort a list and then binary search it if it have to be sort everytime

[tranquil thicket]

Sorting take O(log(n)*n)
Binary search takes O(log(n))

While using just linear search take O(n)

[tranquil thicket]

That not sorting

[finite lotus]

I feel so stupid.

F

[tranquil thicket]

So where is sorting

[finite lotus]

How can I sort through a linked list??

[tranquil thicket]

You could but that's unreasonable

You can gather all node in a linkedlist

Into a single list

And then sort them by hash

Of the value

And reconstruct the linkedlist

[finite lotus]

Ok thanks

!close

[clear swallow]

Python help channel closed

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