Implementation of singly linked list in Dart

[nandikajain]

Welcome to Dart community

Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

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. To ease review, please open separate PRs for separate algorithms.
• All new Dart files are placed inside an existing directory.
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[Parowicz]

Hello! Looks like we already have Linked List implementation. Could you point differences between already existing one and your proposal?

You could also reuse test cases from existing implementation.

[nandikajain]

Oh!
Since it was not in the Linked List folder, I did not notice. The linked List folder only had one code for circular linked list.
I guess it should be moved in the linked list folder then!

[nandikajain]

Will this PR be considered under Hacktoberfest?

[Parowicz]

Well, only if merged.

[nandikajain]

Okay, I will add the implementation of Doubly Linked List, will it be considered?

[Parowicz]

Yea, we don't have any implementation of doubly linked list yet.
List of implemented algorithms can be found in DIRECTORY.md