Add doubly_to_singly() method to convert a doubly linked list to a singly linked list

[F-Blaze]

Describe your change:

• Add an algorithm

This pull request adds a new method doubly_to_singly() to the DoublyLinkedList class.

The method converts a doubly linked list into a singly linked list by creating a new singly linked list and copying the data from each node.

The implementation includes:

• type hints
• doctest examples
• a unit test in test_doubly_linked_list()

Checklist:

• I have read CONTRIBUTING.md
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass automated testing.
• A Wikipedia reference has been included for the algorithm.

[F-Blaze]

Hi maintainers, just a gentle reminder on this PR whenever you get a chance to review it. All checks are passing and I’ve addressed earlier issues. Please let me know if any changes are needed.

[F-Blaze]

Hi maintainers just an another remainder, can you please review the code when you are free.

Thank you

[F-Blaze]

Hi maintainers, I just wanted to know if any changes or updates that are required for this pull request.

Thank you

[F-Blaze]

I was just wondering if there is anything wrong with my pull request cause it has not been reviewed for at least a month.

[jgohel9902]

Consider importing only the required class (e.g., from ... import Node) instead of the full module to improve readability and reduce repeated singly_linked_list.Node usage.

[F-Blaze]

Thanks for the suggestion, I’ve updated the import to use SinglyNode directly and refactored the code accordingly.