Much to my surprise, a newspaper regular puzzle has caught avid interest among people of all age. While crosswords remained a riddle for the selected few, that is not quite the story of sudoku. Even grandmothers and children of young age find this simple looking (but not that easy compared to word jumble riddles) puzzle fascinating. It is not that, old people never dared to solve puzzles, but the percentage is what is stunning. Well, the completed sudoku grid will form what Euler (Leonardo Euler) called the Latin square. He wouldn’t have ever imagined that, three hundred years later ordinary people (not just mathematicians) would play with it so often! More often that not, you may find kids with little sudoku books, trying to put numbers in the 9×9 grid, while on trains and buses and parks. I for one, was of the early opinion that, it is kids game. But once you get a kick of it, then it is very intimidating and often addictive. Much like crosswords (and another craze in the school and college days was carom, even though that didn’t call for anything intellectually stimulating as a word or number puzzle game). Some are very easy (you can fill it in a brisk), some medium level and some hard, when it comes to easiness of solving. There are also ‘very hard’ category, which takes some serious search and scan to get through.

Well, the popular sudoku is a 9×9 grid. It is fanciful to think of an arbitrary numbered square grid. Interestingly, I found a paper which proves that this is an NP complete problem [1]. Well, of course a 9×9 program can be easily programmed and solved by a computer. Fun of course is solving manually. The beauty of this little puzzle is that, this doesn’t require any further background. For the same reason this attract interest from all ages. I heard that there are people buy multiple newspapers just to get that extra sudoku game. Not a bad market idea for newspapers yeah?

Even though Euler did discuss about Latin squares, this puzzle in the current form has a somewhat recent origin. According to Wikipedia, this game in its modern version was invented by Howard Garns, in 1979 and published by Dell Magazines under the name “Number Place“. Having said that, the craze spread all over very recently, perhaps one or two years old craze! Once thing for sure. This small riddle is definitely going to simulate some minds locked far from any puzzles for long. For them this is just an appetite to stimulate some portion of their brain, left idle for long!

Well, for details, there is always Wikipedia. The name itself stands for “the digits must occur only once”, when translated to English (from Japanese. It is Sujiwa Dokushin ni Kogiru)

[1]http://www-imai.is.s.u-tokyo.ac.jp/~yato/data2/SIGAL87-2.pdf