Adding DMOJ

[ghost]

Hey there!, Thanks for submitting a PR to this repo :smiley:
Please complete the following checklist for your PR to be approved. Mark the items by adding an x.
Example: - [ ] Mark me as completed
To mark: - [x] Mark me as completed

• [X] My Pull Request adheres to the Contribution guidelines.
• [X] I have added problem.md and solution files in the appropriate folder.
• [X] In problem.md I have provided a correct link to the problem.
  (In case you are not adding a problem, you can freely mark this as complete)
• [X] The solution I have given is my own and not plagiarized in any form.
• [X] My solution passes all the testcases within the given constraints.
• [X] I have properly indented and documented my solution using comments.
• [X] I agree that all the above marked are true to the best of my knowledge and my PR can be closed if found otherwise.

If any of the above is unmarked, please make the necessary changes and then mark them so that you're PR can be approved and merged.
(Only completed checklist PRs will be reviewed)

[boring-cyborg[bot]]

Hi there :wave: Congratulations on sending your first PR here :sparkles: Your PR will be reviewed soon, in the meantime it would be great if you could star :star: this repo :smiley: