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

40 posts
• Page **1** of **3** • **1**, 2, 3

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

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 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...

Can't wait for your reply!

Havard

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 . . |

+-------+-------+-------+

Can't wait for your reply!

Havard

- Havard
**Posts:**377**Joined:**25 December 2005

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

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

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

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.

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.

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

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
`000001002`

010020030

400500000

004000006

070030010

800000900

500008000

000010070

006400500

Your program output is:

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

- unkx80
**Posts:**7**Joined:**26 August 2006

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.

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.

Took about 10 seconds. Evidently not as fast as your spreadsheet.

Mac

- QBasicMac
**Posts:**441**Joined:**13 July 2005

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

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

40 posts
• Page **1** of **3** • **1**, 2, 3