CS50x Puzzle Day 2026

Hello world, my name is David Malan, and I teach CS50, a free introduction to the intellectual enterprises of computer science and the art of programming with and without artificial intelligence, freely available at cs50. edx. org. Each year we host an event at Harvard University called CS50 Puzzle Day during which students tackle a packet of puzzles, logic problems of sorts, for fun and fabulous prizes. And each year we also hold an event called CS50x Puzzle Day, which is an online adaptation of the same open to everyone around the world whether taking CS50 or not. No prior computer science or programming experience is required. You're encouraged to form a team of size 2, 3, or 4, or you can participate on your own, and teachers are welcome to host their own version during class. Now if you need help forming a team, no matter where you are in the world, reach out to others via any of CS50's communities. You're welcome to collaborate on the puzzles when the time comes via WhatsApp, Zoom, or any other platform. To participate in CS50x puzzle day, register at cs50. ly/register. This is CS50.