Su Doku

I have just been introduced to the puzzle called Su Doku. I enjoy logic puzzles, and while this one has very simple rules, it is pleasantly challenging. 'Not so challenging as to be too frustrating, but enough so that I will stick to pencil for now. (a coworker solves them in ink!)

The premise is a 3 by 3 grid, with each square subdivided again into 3 X 3's making it 9X9 overall. The goal is to fill in the digits one through nine while never repeating a digit in either a row, a column or a square. You are presented with a smattering of digits already placed and you must complete the grid.

I have seen smaller grids in books, as well as larger grids requiring letters to allow for enough unique characters. There are also grids with different geometric delineations to restrict the duplicates (two criss-crossed squares etc) and even one that requires that no duplicates be entered in either of the two diagonals.

My father has written an app to assist in solving (managing your digits) but I have not yet seen this. I have been playing with FileMaker Pro to design a workspace, with varying degrees of assistance.

The book my father gave me suggests jotting in the possible numbers as you find clues, but I prefer to use elimination. I mark tiny x's in the nine positions within a square until I have only one possible number left. Then i erase the x's and write the number. Unfortunately, sometimes by the time I have erased the marks, I have forgotten the number and have to figure it out again. :]

This is where the FileMakerPro would be convenient. I have even considered using Excel as a workspace, but with FMP I could make a stand-alone app, if I ever work it out to my liking. If I do get there, I will make the app available perhaps.

I am curious about the rules for generating these puzzles. They always indicate the difficulty level. Are there more than one possible solutions for the easy ones, or simply more obvious correct numbers?

OK, it is time to go check woot.com and then go to bed.

Cheers.

Su Doku
Woot!