CS50x Puzzle Day 2026

Hello, world! CS50x Puzzle Day starts anytime after 00:00 on Friday, April 3, and ends anytime before 23:59 on Monday, April 6, in your own time zone. Register at https://cs50.ly/register. 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. See https://cs50.medium.com/this-was-cs50x-puzzle-day-2025-914514e76a9d 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! *** This is CS50, Harvard University's introduction to the intellectual enterprises of computer science and the art of programming. *** HOW TO SUBSCRIBE http://www.youtube.com/subscription_center?add_user=cs50tv HOW TO TAKE CS50 edX: https://cs50.edx.org/ Harvard Extension School: https://cs50.harvard.edu/extension Harvard Summer School: https://cs50.harvard.edu/summer OpenCourseWare: https://cs50.harvard.edu/x HOW TO JOIN CS50 COMMUNITIES Bluesky: https://bsky.app/profile/cs50.harvard.edu Discord: https://discord.gg/cs50 Ed: https://cs50.edx.org/ed Facebook Group: https://www.facebook.com/groups/cs50/ Faceboook Page: https://www.facebook.com/cs50/ GitHub: https://github.com/cs50 Gitter: https://gitter.im/cs50/x Instagram: https://instagram.com/cs50 LinkedIn Group: https://www.linkedin.com/groups/7437240/ LinkedIn Page: https://www.linkedin.com/school/cs50/ Medium: https://cs50.medium.com/ Quora: https://www.quora.com/topic/CS50 Reddit: https://www.reddit.com/r/cs50/ Slack: https://cs50.edx.org/slack Snapchat: https://www.snapchat.com/add/cs50 SoundCloud: https://sou