CS50x Puzzle Day 2022

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What is CS50x Puzzle Day?

Solve a packet of problems!

CS50x Puzzle Day is an online adaptation of an event we hold at Harvard each year, an opportunity to collaborate on a team with classmates, family, and friends on a packet of puzzles (i.e., logic problems). The event is open to everyone around the world, whether taking CS50 or not. No prior CS experience required. Teams of size 2, 3, or 4 are encouraged, or you can participate on your own. If collaborating on a team, you MUST collaborate online via chat, voice, or video (unless you already live together).

Starts anytime after 00:00 on Friday, 1 April 2022, in your own time zone. Ends anytime before 23:59 on Monday, 4 April 2022, in your own time zone.

Register officially at cs50.ly/register anytime before 23:59 on Monday, 4 April 2022, in your own time zone. Every member of your team should register individually by submitting the form as well.

See cs50.medium.com/this-was-cs50x-puzzle-day-2020-95176423293c for a summary of a past CS50x Puzzle Day as well as some past puzzles for practice. Indeed, the best way to practice for this year is to solve past puzzles first!

How does it work?

  • Anytime after 00:00 on Friday, 1 April 2022, in your own time zone, your team will download a packet of puzzles as a PDF from cs50.ly/puzzles.
  • Your team will then have until the end of Monday, 4 April 2022, in your own time zone, to solve as many puzzles as you can. You’ll submit your answers online via a Google Form at cs50.ly/submit.
  • Take photos while you work on the puzzles (or screenshots of your team collaborating online)! We’ll then share them online if you’d like.
  • On , we’ll hold a live, Zoom-based walkthroughs of the puzzles’ answers. If unable to attend live, you can also watch on demand afterward.
  • CS50 certificates will be awarded to the teams that answer the most questions correctly.
  • Puzzles will not require prior programming experience, just logic and smarts. All you’ll need is a computer with Internet access, a pen or pencil, and scratch paper.

What are the rules?

  • Teams of size 2, 3, or 4 are encouraged, but you may form larger teams of reasonable size. (You’ll declare your team when you submit your answers.) Consider, though, that the larger your team, the less each team member will be challenged by puzzles! Teams deemed by CS50’s staff to be of unreasonable size will be disqualified and ineligible for certificates.
  • Teams may not share hints or answers with other teams. Teams deemed by CS50’s staff to have shared hints or answers with other teams will be disqualified and ineligible for certificates.

See CS50x Puzzle Day 2019’s discussion of honesty for context!

What are the puzzles?

They’ll appear here at 00:00 on Friday, 1 April 2022, in your own time zone!

How to practice?

The best way to practice for this year is to solve some past puzzles first!

Looking for teammates?

Post in any of CS50’s communities if looking to form a team! Perhaps share a little bit about yourself in your post.

Quotes from last time!

  • “A good activity to do with friends!”
  • “Difficult, Challenging, but most of all, Memorable!”
  • “Extremely fun but mind boggling at the same time”
  • “Great fun, and I think I even have a few non-grey hairs left!”
  • “Had the best online experience of my life. Got a chance to get to know many people from different countries. Absolutely loved the experience.”
  • “I can describe CS50 Puzzle Day in one word as Awesome. It’s just wonderful, I feel so confident after making new friends from other parts of the world, solving puzzles with them which improved my team coordinating skills. I have learned so much from the competition and my new friends and I would love to take part in this competition every year.”
  • “It was a lot of fun and a great way to use your mind in a different way than you usually do day to day.”
  • It’s brainwreckingly good!”

Photos (and memes)!

Take photos (and create CS50x Puzzle Day-related memes) while you work on the puzzles (or screenshots of your team collaborating online)! Then submit them at cs50.ly/photos!

Questions?

If you have a question about a puzzle, email puzzles@cs50.harvard.edu, and we’ll do our best to reply! Afraid, though, we won’t be able to offer any hints or tips!

How to submit?

Submit your answers at cs50.ly/submit by 23:59:59 on Monday, 4 April 2022, in your own time zone!

Who are the winners?

Check back here a few days after Monday, 4 April 2022, in your own time zone, to see who’s won CS50 certificates!

What are the right answers?

On , we’ll lead Zoom-based walkthroughs of the puzzles’ answers!

To attend the walkthroughs, download and install Zoom from zoom.us/support/download, test your connection at cs50.zoom.us/test, and then log into cs50.ly/solutions just before ! Or, if your internet connection isn’t fast enough for video, you can attend by phone by calling one of these numbers.

If unable to attend live, you can also watch the walkthroughs on demand afterward.