Invitation to CS50x Puzzle Day 2025

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, friends, students, and colleagues 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. Teachers are welcome to host their own version during class.

Starts anytime after 00:00 on Friday, April 4, 2025, in your own time zone. Ends anytime before 23:59 on Monday, April 7, 2025, in your own time zone.

Register at cs50.ly/register anytime before 23:59 on Monday, April 7, 2025, in your own time zone. Every member of your team should register individually by submitting the form as well.

See / this-was-cs50x-puzzle-day-2024 for a summary of last year’s 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!

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This is CS50, Harvard University's introduction to the intellectual enterprises of computer science and the art of programming.

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