CS50x Puzzle Day 2017 around the World

David J. Malan

On Friday, 31 March 2017, began CS50x Puzzle Day 2017, the second-ever online adaption of CS50 Puzzle Day, the first of @CS50’s events each fall at Harvard (and now Yale). To allow students across time zones to partake, CS50x Puzzle Day (er, Days) again spanned a weekend plus two weekdays (so that CS50 AP classrooms could participate during school).

7,986 students and teachers from 1,858 cities in 152 countries registered in advance, up from 3,792 last year. And 297 teams comprising 750 participants ultimately submitted solutions. Among those that submitted, most participants are taking or haven taken CS50x (57.2%). Many (31.6%), though, are not (yet)! Of the teams that responded, most (60.9%) found the puzzles too hard, though quite a few (38.3%) thought the puzzles’ difficulty just right. Two teams (0.8%) felt the puzzles were too easy. (I was on neither of those teams.)

Puzzles’ perceived difficulty by respondents.

This year’s puzzles were crafted by Matthew Warshauer ’14 of Facebook and CS50’s own Doug Lloyd ’09. At the stroke of midnight on Friday were participants invited to download the packet below!

Here come the spoilers. Solutions ahead!

JOLT ORGANIZATION CHECK DRACULA or NOSFERATU PRISM DAHSHUR or CAIRO or DASHUR or EGYPT BONDS or BARRY BONDS or WILLIE MAYS DRAGON

For the puzzles’ postmortems, here’s Doug (on the new set of CS50 Live)!

Puzzle #5 was perhaps this year’s hardest, with only seven teams solving.

Quite a few teams solved one or more puzzles, but only three teams solved all eight!

Indeed, this year’s winning teams are…

pH7 Brainz from Gothenburg, Sweden

from Gothenburg, Sweden ROVR from San Francisco, California, USA

from San Francisco, California, USA The Smoked Paprikas from Basking Ridge, New Jersey, USA

And tied for second place are…

god knows from Melbourne, VIC, Australia

from Melbourne, VIC, Australia HWHS Math Club from Halifax, Nova Scotia, Canada

from Halifax, Nova Scotia, Canada naruto ninjas from Plano, Texas, USA

from Plano, Texas, USA TAMS from Denton, Texas, USA

from Denton, Texas, USA Team from Albuquerque, New Mexico, USA

from Albuquerque, New Mexico, USA Team Herbie from Philadelphia, Pennsylvania, USA

from Philadelphia, Pennsylvania, USA Trinity Arrows from United Kingdom

from United Kingdom Turing Machine from Berkeley, California, USA

Each of these teams will soon be receiving a certificate from CS50 via email!

And here’s how every team fared.

This was CS50x Puzzle Day 2017 around the world.