I'd be using this post to help organize good problems which are lacking worthy solutions.
If you would like to see a solution to a particular problem, please state the problem title, provide a link to it and also state the topic. You can also @mention the creator, so that she/he is made aware. If the problem was already listed, you can upvote the comment. To keep this list reasonable, these problems should have been posted for at least a week.
If you added a solution to the problem, please reply to the comment. Once your solution has been upvoted several times, I'd then clear out the comment, so as to keep things fresh. (Do not post your solution as a reply)
Once someone has added a solution, I will push the comment to the top. Please can check their solution, and provide some feedback on it. If you have a different approach, add it and enlighten all of us.
Kudos to the following for writing solutions.
1. Jatin Yadav \( \times 3 \)
2. Siddhartha Srivastava
3. Kumar Gupta
4. Jon Haussman
5. Beakal Tiliksew
6. [Happy melodies}(https://brilliant.org/profile/happy-a75fqm/feed/)
7. Pranav Arora \( \times 2 \)
8. Nathan Ding
9. N K
10. Ariel Gershorn