# The Cody Fifth Anniversary Challenge

Does Cody have birthdays or anniversaries? It seems to me like it should have birthdays, but anyway, it’s been around for five years (actually, almost six by now). Back in October, we announced a contest in honor of Cody’s fifth. The really cool thing about this contest is that a panel of distinguished Cody problem authors created a raft of special anniversary puzzles for us. One list consisted of easy problems, and the other list was hard.

The contest ended with the new year, so now we see the results. First of all, it was a great success! Lots of new problems, lots of new players, and lots more solutions overall. Of all the Fifth Anniversary problems, the one with the most Likes was Peng Liu’s MATLAB Counter, in which you use nested functions to make a stateful counter. Even though it was in the easy list, it was difficult in the sense that only 21% of the solutions were correct. But I’ve seen this pattern before; the most satisfying problems are often the ones where you have to work hard but you learn a genuinely valuable new skill.

Incidentally, another “easy” problem that had a similarly low correct/incorrect ratio was James’s Tick Tock Tick Tock. Only 20% of the solutions were correct. But the problem was actually a one-in-five lottery. You had to submit your solution at a time when the number of seconds was divisible by 5! The last “hard” problem was also the very hardest, at least as measured by fewest solvers. It was a fiendish 3-dimensional sliding block puzzle and it too was among the most liked: The sliding puzzle 3D by HH.

Here are all 17 badge winners and when they first won their prizes. This is a mighty accomplishment, and this limited-edition badge will never be awarded again.

23 Oct: Alfonso Nieto-Castanon, Daniel Turizo
30 Oct: LY Cao
2 Nov: Daniel Meier
20 Nov: Corneli Keim
27 Nov: HH
30 Nov: Daniel Rubin
14 Dec: Josh
17 Dec: Osman
21 Dec: goc3Ziheng Hu
23 Dec: Binbin Qi
29 Dec: TimGunther S
31 Dec: Thomas SteffenPeter CookBrendan Gray

Congratulations to all these badge winners! I should also point out that, while our special Cody 5 badge competition is over, the problems themselves are still open to all solvers.

The fifth anniversary also included a raffle. To get entered into the drawing, you just needed to solve one problem, whether from the easy or the hard list. Here are the lucky winners, week by week.

23 Oct: Yehe Liu, Joel Cottrell
30 Oct: Pavol Michalina, Gnaneswar Nadh satapathi
6 Nov: mustafa, James
13 Nov: Heiko, Li jw
20 Nov: Sanghai Guan, Viko
27 Nov: jzv, Elmar Zander