This looks really good @anu0012 :) I've suggested a few more topics but feel free to disagree with me :)

A couple of suggestions for the future. Please only tackle one issue per PR. Doing several issues per PR makes it harder to review and it means additions that are good to go can be held up by changes needed elsewhere. For example, if you had made these separate PRs I would have been able to merge the topics for bracket-push and atbash-cipher straight away.

Also, it's a good idea to do your PR changes on a separate branch on your fork, not on your master branch. Any commit you now push on your master branch will appear in this PR which means it's easy to accidentally push unrelated things to your PR, and it's harder for you to keep doing other work while your PR is being reviewed.

Those are just minor things to bear in mind for the future. Thanks for taking the time to contribute :)