Two days ago, Bob Lee posted a fun challenge on the Luhny Bin. It was not before a day has passed that I could get to know of the problem and try my hands at it. The delay being attributed to absence of Cygwin on my Windows machine which was needed to run the test harness (refer original post on details).

Yesterday, I spent most of my time first trying to get the harness running without using Cygwin. The solution was a bit tricky as I had to figure out how the test harness was actually running. Anyhow, my solution is available at here wherein I modified the original file. The change was simple: first, change on line 41 to say mask.bat and second, modify line 81 to correctly build the process.

Once, I had it setup and after loosing all day, I was ready to start coding the actual solution. Before I dozed off to my bed, I had made sure that my code passed 18 of the 20 tests. The 19th test was tricky. It had many over-lapping luhn numbers, and hence I had some leftover in the end which was not being cleaned up. This single test made me completely rewrite the piece introducing a third buffer (which came down to two, as I directly now wrote to System.out.

Anyways, the solution is now complete and posted on my fork of the LuhnyBin Github repository.