CS50x Puzzle Day 2020

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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, 3 April 2020, in your own time zone. Ends anytime before 23:59 on Monday, 6 April 2020, in your own time zone.

Register officially at cs50.ly/register anytime before 23:59 on Monday, 6 April 2020. Every member of your team should register individually by submitting the form as well.

See medium.com/@cs50/this-was-cs50x-puzzle-day-2019-c98112adb467 for last year’s puzzles and solutions. Indeed, the best way to practice for this year is to solve last year’s puzzles first!

How does it work?

  • Anytime after 00:00 on Friday, 3 April 2020 (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, 6 April 2020 (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.
  • After Monday, 6 April 2020, we’ll post some walkthrough videos in which we’ll explain the (correct!) answers.
  • 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 last year’s discussion of honesty for context!

What are the puzzles?

Here is a PDF of the packet of puzzles that you can download and/or print!

Packet of Puzzles

Looking for teammates?

Visit cs50.ly/teammates!

Quotes from last year!

  • “I met amazing people and I had so much fun. Thank you :)”
  • “my mind was blown away with these puzzles and i’m looking forward to it next year”
  • “Enjoyed it very much and fried my brain”
  • “This has been a lovely experience. Not only has it challenged me and everyone on my team, but it made me reach out to other people from different countries and get out of my comfort zone. I will definitely be doing this next year.”
  • “This is exceptionally good competition. I’m very greatful to organizers. I hope that people all around the world who were solving this puzzles are as happy as me.”
  • “The real answer was the friends we made along the way”
  • ”[**] that was hard”

Photos (and memes)!

Take photos (and create CS50x Puzzle Day 2020-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, 6 April 2020, in your own time zone!

Who are the winners?

Check back here a few days after Monday, 6 April 2020, to see who’s won CS50 certificates!

What are the right answers?

Right here!