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Winter is Coming: Warm Your Brain Cells With a Java Developer Puzzle

Holidays are very often great for hacking, besides other things like building medieval landscape puzzles in your kitchen. This is the time of year when there are less deadlines, less going on. If you don’t want to undertake a big project then we have something for you. A holiday puzzle. This time we’ve taken a step away from our historical puzzles and done this a little differently….

The goal of this puzzle is to implement a function that would satisfy a list of unit tests:
. I hope you’ve heard about unit tests? Right? You will also need to install Gradle and have Mercurial ready.

Your task is to figure out which function we are testing and implement that function for us. If you have a solution, you should tweet us your repository URL @jrebel, and in the beginning of January we’ll go over those repositories and see who of you was a good hacker :) Are you brave enough to challenge our puzzle? Also big thanks go to @shelajev and @t4ffer.

  • tino

    What is the solution? Im very curious.

  • michael

    Yeah, me too.

    I spent a few hours and got to a point where two thirds of the tests would pass. But I had some difficulties with the tests that contained the large numbers. Couldn’t figure out the modulus …

  • Toomas Römer
  • Toomas Römer

    We are thinking about showing the solution, hopefully a blog post in a week will answer that. We did realize that this puzzle was a bit too difficult and not enough steps that would fuel to continue to solve it. I’ll keep you posted.

  • Toomas Römer
  • Dale Wyttenbach


  • Toomas Römer

    Sorry about the delay! The solution blog post has been written and sent off to editing and going out soon! I’ll ping this thread once done.

  • Toomas Römer