## Finally A Way To Solve All Sudoku Puzzles!!

Post the puzzle or solving technique that's causing you trouble and someone will help

### Finally A Way To Solve All Sudoku Puzzles!!

Hey Guys,

Check this site out. It'll help everybody learn all the methods needed to know for solving. www.bestsudokusecrets.com

Happy Sudoku everyone
SarahJ

Posts: 2
Joined: 02 November 2006

Hi SarahJ.

Welcome to this forum.

Carcul
Carcul

Posts: 724
Joined: 04 November 2005

Hi SarahJ and welcome to the forum!

I have this puzzle I have been struggling with a bit lately! I was wondering if you could give me some ideas for how to start with this puzzle, say, to show me how I should go about to place the 3-4 first numbers? I saw on your website that you are a sudoku-pro and I can't wait to get some professional advice on this one! If your advice is as good as I hope it is, I will purchase you book for sure! (and I am sure all the other member who read your solution-suggestion will purchase your book too!)

This is the puzzle in question. It was published in a newspaper in my "area" a little while back, but I can't seem to crack it! I even have trouble placing my second number...
Code: Select all
`+-------+-------+-------+ | 1 . . | . . 7 | . 9 . | | . 3 . | . 2 . | . . 8 | | . . 9 | 6 . . | 5 . . | +-------+-------+-------+ | . . 5 | 3 . . | 9 . . | | . 1 . | . 8 . | . . 2 | | 6 . . | . . 4 | . . . | +-------+-------+-------+ | 3 . . | . . . | . 1 . | | . 4 . | . . . | . . 7 | | . . 7 | . . . | 3 . . | +-------+-------+-------+ `

Havard
Havard

Posts: 377
Joined: 25 December 2005

Yes, I'll definitely solve it for you. I'm at work right now but will take a look when I get home tonite.
SarahJ

Posts: 2
Joined: 02 November 2006

Hi,

I await Sarah's solution with interest. In the meantime, could Harvard please tell me the name of the newspaper it came from? Just so that I don't pick it up (which I normally do for the Sudoku puzzle) if I find a copy on any part of the London Transport network.

Thanks

Andrew D
andrewd

Posts: 7
Joined: 27 July 2006

Don't worry, I suspect that it came from a very cold part of FINLAND

if a non Finnish puzzle is required, I suggest one of my fluid drives or ultimaltely Ocean's most recent diamond

tarek

tarek

Posts: 2973
Joined: 05 January 2006

tarek wrote:Don't worry, I suspect that it came from a very cold part of FINLAND

Either that, or Norway (where Havard's from) or Sweden...

These Nordic folks are certainly in a different class from the rest of us... Keep an eye on the competitors from Scandinavia in the upcoming World Sudoku Championship!

Meanwhile, we're all eagerly looking forward to Sarah's reply...
udosuk

Posts: 2698
Joined: 17 July 2005

### solving sudoku

I offer SarahJ the program below free of charge.

http://homepages.ipact.nl/~allersma/all_lab.htm#soft

However some manual help is needed. So if you place a 6 and a 2 at the right location the puzzle become very simple.
Last edited by merallas on Wed Nov 08, 2006 8:42 pm, edited 1 time in total.
merallas

Posts: 39
Joined: 26 September 2006

This puzzle required me to find eight numbers by trial and error to solve. The most I ever experienced before was 5. I can't believe I found these numbers so fast on my spreadsheet so I'm going to have to reverse my search algorithm and check for multiple solutions:

160/007/490
534/120/608
709/600/500

405/300/900
010/080/002
600/004/000

300/000/010
040/000/007
007/000/300

So I reversed the search algorithm and only needed 5 additional numbers to solve:

100/007/090
030/020/008
009/600/500

005/300/900
013/080/002
608/004/100

306/000/010
040/000/067
007/000/300

This yields the same solution, so I presume it is unique.

The one posted below by unkx80 was a real bear. It required finding 5 numbers for the forward algorithm and 6 for the reverse but the solutions were the same. I run the algorithms manually, so this method would be much slower than a program.
Last edited by Len on Tue Nov 14, 2006 2:05 pm, edited 1 time in total.
Len

Posts: 25
Joined: 04 August 2006

### sudoku

Ok, the 6 is now in the right location. If you find the 2 the puzzle can be solved using naked single, naked pair or single cell.
merallas

Posts: 39
Joined: 26 September 2006

### Re: solving sudoku

merallas wrote:I offer SahraJ the program below free of charge.

http://homepages.ipact.nl/~allersma/all_lab.htm#soft

On your page you ask for people to send sudokus your program cannot solve. Here is one, taken from http://diuf.unifr.ch/people/juillera/Sudoku/InterestingSudokus.html (last one in "Beyond Forcing Chains")

Code: Select all
`000001002010020030400500000004000006070030010800000900500008000000010070006400500`

Code: Select all
`random method not possible; hit key to stop`
unkx80

Posts: 7
Joined: 26 August 2006

### solution

Hello unkx80,

Because there is only one cell with two possibilities this sudoku requires some additional handwork. So if you make e.g. r9c9=9 the program will solve the puzzle. It is quite easy to find this by trial and error. In the future I will expand the program by a routine which test the possibilities of each cell one by one in cases of sudoku like this one.
merallas

Posts: 39
Joined: 26 September 2006

Len wrote:This puzzle required me to find eight numbers by trial and error to solve.

Me, too. I use a program I wrote in QBasic. It reported only one solution, while exhausting all possible guesses.

Mac
QBasicMac

Posts: 441
Joined: 13 July 2005

### Re: solving sudoku

Hi unkx80,
In the mean time I have added more powerfull routines to solve difficult (almost impossible) sudokus. Some patient is required in some cases. So I invite you to find again a sudoku which cannot be solved by my program.

By the way, thanks for the link to "InterestingSudokus". It is a very nice overview of the sollution methods.

regards,
Merallas
merallas

Posts: 39
Joined: 26 September 2006

Merallas, check out this thread, if your program could solve the bulk of those puzzles I'd say it's very close to being complete...
udosuk

Posts: 2698
Joined: 17 July 2005

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