Solving Kurosu

What it was

This Christmas I encountered ‘Kurosu’ – a japanese grid-based logic puzzle in the same vein as Sudoku (albeit a lot simpler than Sudoku).

As a Christmas puzzle – and to top-up my coding skills development over the holiday – I set myself the challenge of writing some code to solve all such puzzles. It took a few hours over several days but I managed it in the end (probably wouldn’t be blogging about it if I hadn’t…)

My code uses simple logical induction to eliminate the puzzle grid’s non-solutions, row-by-row and column-by-column.

You can find it at:

If you don’t want to run it youself you’ll have to take my word for it that it works!

What I learned

Part of the challenge was that I wasn’t allowed to look at anyone else’s solution to this until after mine was working.

I confess admiration for this (very different) solution, which takes a more combinatorial / number-crunching approach – generating the set of all possible valid solutions then simply testing which one is at a hand. Plus – his taut PERL scripting makes my Python look laughably clunky and byzantine!

But I’m trying not to feel completely inadequate – my approach roughly emulates the process a human would use to solve the grid and needs relatively few (4 or so) iterations to settle on a solution.

What I will aim to do differently as a result

  • Keep brushing up on my coding – still so much to learn
  • Reflect on different approaches to coding and problem solving – think about efficiency not just efficacy of code

Note: I went back and edited this post into my usual learning format after publishing it.