It looks like you're the only one interested in a real challenge thus far, John. So let me give you a little info:
These puzzles consist of a grid with 9 rows and 9 columns, divided into 9 3x3-square "boxes" and 81 squares (9 squares to a box).
Each puzzle has several of the squares already filled in with a number between 1 and 9. The "easy" puzzles have between 35 & 40 squares already filled in, while the "medium" and "hard" ones have between 25 & 30 squares filled in. I haven't even tried the "very hard" puzzles yet.
The objective is to fill in the remaining (blank) squares so that each row, column and box has each of the numbers from 1 to 9. Let me tell you, it isn't easy (especially as you start out), but it sure is very challenging and absolutely addictive. A couple of tips:
1) start out by recording at the top of each of the blank squares all of the possible numbers that can be put into that square, remembering that each digit (1-9) can appear only once in each row, column or box. So if the square you're working is in a row already having numbers 2 and 8; in a column having the numbers 5, 7 and 8; and in a box with the pre-existing numbers 2, 5 and 9 , the only numbers that can go into that square are 1, 3, 4 and 6 (numbers not already in the associated row, column or box).
2) once you've written (as small as you can) all of the "possible" numbers in each of the blank squares, you're ready to begin solving the puzzle. If only one number shows up in a blank square (it happens occasionally), then you have a no-brainer and you post that number in that square. As for the remainder, you have to start scanning a) the rows, then b) columns, and finally c) boxes for clues as to which number actually belongs in each blank square. For example, if a number appears in only one square in a row, column or box, then you record that number in that square. By process of elimination, you fill in the rest of the squares until every row, column and box has the requisite numbers 1 thru 9. Are you still with me, bubba?
3) don't guess
at which number goes into any square. You have to figure it out logically and mathematically...no guessing! You'll see what I mean as you get started. Begin with the "easy" puzzles, and slowly work your way up to the tougher ones as you gain confidence and skill.
The following website is the best that I've found on the subject: http://www.dailysudoku.co.uk.
Go to "SuDoku Archives", where there are 200 puzzles from Jan.'05 thru July'05. Choose an "easy" puzzle (the're classified as easy, medium, hard and very hard) and print it out. If you then drop down just under the puzzle, you can get and print the solution. However, that should be just a fallback if you run into trouble. I print the solution (without looking at it, of course) on the back of the printed puzzle. So far, I've had to resort to "cheating" only once or twice.<G> It's a lot more fun if you can do it all by yourself.
Good luck. I hope that some of the lurkers out there will get involved with this craze as well, John. I'm sure they and you will find it fascinating. There are books out on the subject, but I haven't bothered to refer to one yet. My sil gave me the same heads-up I'm now giving you, and I've gone from there on my own. If you dig the program "NUMB3RS", you'll really enjoy Sudoku.
Post Edited (07-24-05 08:29)