Elisabeth asked:


Instructions:

There are 9 rows of numbers across and 9 columns of numbers down.
Numbers 1 through 9 need to go across and down.
You can only use each number once in each row, column, or 3×3 square.

l _ l 7 l 6 ll _ l 9 l 5 ll _ l 2 l _ l
l 1 l _ l 8 ll 3 l _ l 4 ll _ l 7 l 9 l
l 4 l _ l 5 ll 1 l _ l 2 ll 6 l _ l 8 l

l _ l 6 l _ ll _ l 4 l 1 ll _ l 8 l 5 l
l 9 l 5 l 2 ll _ l 3 l _ ll 4 l 6 l 1 l
l 8 l 4 l _ ll 5 l 2 l _ ll _ l 9 l _ l

l 6 l _ l 9 ll 2 l _ l 7 ll 8 l _ l 3 l
l 2 l 8 l _ ll 4 l _ l 3 ll 9 l _ l 6 l
l _ l 3 l _ ll 6 l 8 l _ ll 7 l 1 l _ l

DJ asked:


I want to schedule a program to build Sudoku easy and systematically but I haven’t no way to make it easy and systematic. The question is : How build a sudoku easy and systemically?
I also want to know that learning to make them by hand, since I have many ways of obtaining them?

Meg A. asked:


This is about Ubuntu netbook 10.10.

I downloaded this file and verified it using md5sum; the hashes match. Then I installed it to a USB flash drive using Unetbootin. When the flash is plugged in my computer will now boot to Ubuntu. But the desktop looks empty.

There is a kind of pinkish-lavender wallpaper there, and I can see two different shaded bars, one on the left side of the screen and one on the top. But there doesn’t appear to be anything in them – until I “mouse over” the one on the left. Then I see blank white boxes.

I can click on these white boxes and open things; last night I was able to find Firefox, play a game of Sudoku, and even connect to the Internet – which is amazing considering my wireless modem is usually not that easy to set up. Since I can open and run things I’m figuring everything – or at least some things – got installed correctly. But it’s all a guessing game about where anything is. There are no icons and no text. I’ve never used Ubuntu before, so I don’t know what it’s supposed to look like. But surely there should be more there than blank white boxes.

What’s going on here? Is it a problem with Ubuntu, or with my computer’s display settings, or is it something else? I deliberately went with the netbook version because it was supposed to work better with smaller screens, and my laptop, while not a netbook, does have a pretty small screen.

And I guess what’s more important, how do I fix it?

Thanks in advance for your help.

[P.S. I did try installing to my hard drive from the flash, and it seemed to be successful, but I can't access that installation to see if the problem exists there too. I guess I should make that a separate question...]

CoffeeAddict asked:


Is there a straightforward method to classify Sudoku games in terms of their complexity, whether they are easy, medium or hard (or any other scale for that matter)?

Also, is there any standardized technique or algorithm (by hand or using some open-source code) for creating Sudoku tables according to a wished level of complexity? Or is there no other way to do it than through a lot of trial and error? Also, how do you know whether you’ve stumbled upon a brand new combination? Is there a list somewhere on the Internet with tried and tested combinations?

One final question, how would you qualify this game below (and why)? Medium? Obviously, it’s not as easy as some others that I’ve tried in that it cannot be solved simply through the filled in blanks alone. But it was not extremely hard either and I can’t imagine there not being anything harder…

l _ l _ l 7 ll _ l _ l _ ll 3 l 5 l 4 l
l 8 l _ l _ ll _ l 1 l _ ll _ l _ l 9 l
l _ l 5 l _ ll _ l _ l 4 ll _ l _ l _ l

l 5 l _ l _ ll 4 l _ l _ ll 9 l _ l 8 l
l _ l 3 l _ ll 9 l 6 l _ ll 1 l _ l _ l
l 9 l _ l _ ll 5 l _ l _ ll _ l 2 l _ l

l 2 l _ l _ ll _ l 3 l _ ll 4 l 8 l _ l
l _ l _ l 3 ll _ l _ l 8 ll _ l _ l 6 l
l _ l 8 l 9 ll 2 l _ l _ ll _ l _ l _ l