A search for “sudoku” on SourceForge.net yields more than 300 projects, so why use HoDoKu to generate, solve, and analyze sudoku puzzles? Creator Bernhard Hobiger gives three good reasons: the number of techniques the software employs, the ability to create several solutions for one puzzle, and the application’s scalable GUI.
Hobiger elaborates: “Over the years sudoku players have developed a large array of techniques to exclude possible candidates from cells. HoDoKu supports more than 90 techniques, more than any other software I know. You can search for all implemented techniques at any given state during solving and display them graphically.
“Several solutions: You can change the solution path, create new solution paths, and compare them. This is something I have never found in another tool.
“Scalable GUI: That was the main reason I started the whole project. Many helper programs have two or three predefined display sizes, and most of them are simply too small for modern large monitors. With HoDoKu you can make the puzzle area as large as you want.”
One of the most useful features of version 2.0, which was released this month, is the training mode. Select Mode -> Learning… from the menu, choose a technique, and create a new puzzle. The program then displays the puzzle in a state where the selected technique is applicable. Advanced users can use the backdoor searcher for creating shorter and more elegant solutions.
Hobiger says he started working on HoDoKu about three years ago, “when a friend introduced me to sudoku. In the beginning I just wanted to write a small tool for myself, but it soon became a bit of an obsession. I have been a teacher for the last 10 years after working as programmer and project team leader in the industry. Although I love teaching, one problem is that you never have a ‘product’ that is really finished and deployed. So I decided to make HoDoKu my product.
“I wrote the software in Java to make it platform-independent, using NetBeans as IDE. I use Launch4J to create an executable file for Windows, wix and WixEdit for the Windows installer, and BrowserLauncher for accessing the user guide on the Net – all SourceForge projects.”
From the beginning Hobiger planned to release HoDoKu as open source software. “SourceForge was always the number one open source site for me, so naturally I put it up there. I can create a web page and make releases without having to think about administration, and without costs, which is really great.”
The developer is still improving the software. “A few techniques are still missing, the puzzle creation should be enhanced (creating puzzles with predefined shapes for example), and users have asked for more printing options. Since I can only work on HoDoKu in my spare time I can’t say exactly when the next release will be available, but I plan to create new releases about every half year in the future.
“It would be cool to port parts of the GUI over to mobile platforms (iPhone and Android come to mind) but I personally don’t have enough time to do that myself. If anybody is interested in doing it (or at least helping with it), I would be glad to get an e-mail.”