As a team last week we decided to work through a “Coding Kata” as a learning experiment. For those unfamiliar with the concept, a Kata is a Japaneese word that refers to a choreographed series of movements. In the context of programming, a Kata refers to repeatedly solving a problem with incrementally improving technique. The challenge we decided to look at was a somewhat contrived Bank OCR problem described on codingdojo.org.

We only looked at “User Story 1” which describes a process for translating lines of ASCII text into the decimal numbers which they represent. The task isn’t particularly hard but what we were interested in was how different people approached the problem, what considerations they had, and where they got hung up. As a group, the consensus approach was to decompose the problem into pieces, decide on data structures, and then sketch out some pseudo code.

  • Breaking down the problem is fairly straightforward. We’re basically looking to read in the file, separate the lines into the “bank numbers”, recognize individual numbers, and then combine the numbers we’ve recognized. An additional benefit of approaching the Kata like this was that individual team members could craft solutions in different programming styles – imperative, functional, etc.
  • Once we had the “big” pieces of the solution, the next thing we flushed out was which data structures to use. After some discussion it was clear that reading the file and recognizing the numbers were related and the data structures used would need to be related. Interestingly, there was a decent amount of debate around what to use to represent the read lines and then how to match them. The team was split between using a 3×3 array versus using a 9 character string.
  • The final step we took was jotting down some pseudo code on a whiteboard to actually perform all the steps. I’ve always found it interesting to watch people code on a whiteboard and this time wasn’t any different. Our team seemed to struggle with visualizing what the data looked like and also how much detail to convey in the pseudo code.

After we wrapped up on the whiteboard we ended up implementing 3 solutions. A functional solution using a 3×3 array for the numbers, an imperative solution also using a 3×3 array, and an imperative solution using a 9 character string to represent the numbers. The solutions are similar but the style of the original author still definitely comes through.

Anyway, how would you have approached a problem like this? We’d love to hear in the comments!

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