Comments on: A Sudoku challenge generator http://blog.forret.com/2006/08/a-sudoku-challenge-generator/ Tango, photography and whatever's bleeding edge Thu, 27 Oct 2011 14:28:42 +0000 hourly 1 http://wordpress.org/?v=3.1.4 By: Generating Sudoku puzzles using JavaScript | CodeUtopia http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-324639 Generating Sudoku puzzles using JavaScript | CodeUtopia Sat, 29 Nov 2008 11:57:33 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-324639 [...] there are some examples of generating sudokus online, such as this interesting approach, it seems there’s only one “true” way: Using a backtracking [...] [...] there are some examples of generating sudokus online, such as this interesting approach, it seems there’s only one “true” way: Using a backtracking [...]

]]> By: Pallavi http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-291874 Pallavi Thu, 28 Aug 2008 08:47:32 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-291874 I am sorry. I mistook Simon as the author of this blog article. My first note was to the author. Simon, you idea is also very good and innovative. I am sorry. I mistook Simon as the author of this blog article. My first note was to the author.
Simon, you idea is also very good and innovative.

]]> By: Pallavi http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-291873 Pallavi Thu, 28 Aug 2008 08:40:25 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-291873 Hi Simon, your article is really good. Its so simple and crisp, yet so complete. Thank you so much for sharing this article. Hi Simon, your article is really good. Its so simple and crisp, yet so complete. Thank you so much for sharing this article.

]]> By: Simon Broadley http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-112964 Simon Broadley Tue, 03 Jul 2007 16:11:40 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-112964 This will always produce variations on a theme - three numbers which start off adjacent will remain adjacent - though in a different order. If anyone fancies a look, I've used an entirely different approach in my Javascript sudoku generator: http://www.picturesudoku.com In essence, it fills in as much as it can, and then solves the puzzle to get the remaining numbers. Best Wishes, Simon This will always produce variations on a theme – three numbers which start off adjacent will remain adjacent – though in a different order.

If anyone fancies a look, I’ve used an entirely different approach in my Javascript sudoku generator:

http://www.picturesudoku.com

In essence, it fills in as much as it can, and then solves the puzzle to get the remaining numbers.

Best Wishes,
Simon

]]> By: Artuzai http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-96750 Artuzai Sun, 20 May 2007 05:46:04 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-96750 This article inspired me to write a Sudoku generator in PHP. Thanks for the good ground-work! However I am finding that even with 6 Mutation rules (Row Swap, Col Swap, Row Block Swap, Col Block Swap, Transpose and Replace) and 100 mutations that the mutated grid shows some patterns. Groups of 3 (either row or column) within one block will always reoccur in the same position in the other blocks. Say, in position 1,1 (top left) we had the numbers 4,7,1 then we also get exactly that set of numbers in the 2nd row (or 3rd row) of the top middle block (in perhaps different sequence) and the same set of numbers also in the 3rd row (or 2nd row) of the top right block. Surely a good mutation sequence would not have necessarily the same set of numbers together :-) http://www.tobiasw.net/Misc/JavaScript/Sudoku2/SudokuX.php This article inspired me to write a Sudoku generator in PHP. Thanks for the good ground-work! However I am finding that even with 6 Mutation rules (Row Swap, Col Swap, Row Block Swap, Col Block Swap, Transpose and Replace) and 100 mutations that the mutated grid shows some patterns. Groups of 3 (either row or column) within one block will always reoccur in the same position in the other blocks. Say, in position 1,1 (top left) we had the numbers 4,7,1 then we also get exactly that set of numbers in the 2nd row (or 3rd row) of the top middle block (in perhaps different sequence) and the same set of numbers also in the 3rd row (or 2nd row) of the top right block. Surely a good mutation sequence would not have necessarily the same set of numbers together :-)

http://www.tobiasw.net/Misc/JavaScript/Sudoku2/SudokuX.php

]]> By: scott http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-95187 scott Mon, 14 May 2007 14:27:36 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-95187 in addition to methods of swapping rows/columns to generate puzzles, you should also be able to swap individual numbers globally. for example, replace every 7 with a 5, and replace every 5 with a 7. in addition to methods of swapping rows/columns to generate puzzles, you should also be able to swap individual numbers globally. for example, replace every 7 with a 5, and replace every 5 with a 7.

]]> By: Xiangyu Cao http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-95053 Xiangyu Cao Mon, 14 May 2007 02:09:34 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-95053 Acctually, I think swap rows and columns can implement transposing already. Acctually, I think swap rows and columns can implement transposing already.

]]> By: Xiangyu Cao http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-95046 Xiangyu Cao Mon, 14 May 2007 01:45:41 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-95046 Cool. Just wondering if step 2 can produce all possible puzzles? If not, what's the percentage? Actually, I think it should be able to produce all possible puzzles. Cool. Just wondering if step 2 can produce all possible puzzles? If not, what’s the percentage?

Actually, I think it should be able to produce all possible puzzles.

]]> By: prasad http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-43759 prasad Wed, 31 Jan 2007 13:45:17 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-43759 enjoyed reading ur article but i have a different algorithm to generate a valid filled sudokus not restricting your shuffling to rows and coloumns..and one more whats that symmetry in sudoku all about... enjoyed reading ur article but i have a different algorithm to generate a valid filled sudokus not restricting your shuffling to rows and coloumns..and one more whats that symmetry in sudoku all about…

]]> By: jovivebo http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-37754 jovivebo Thu, 18 Jan 2007 20:15:41 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-37754 I recently read an article about sudoku in the newspaper. From a mathematical point of view it seemed a lot more complicated than I had expected. It is eg. still unknown to mathematicians how many sudoku challenges there are. Remember here that a true soduku has one and only one solution as mentioned above ! The article mentioned that there was one mathematician who though that you could have a sudoku with 16 remaining cells and a unique solution. It remains to be proven though. I believe the best any mathematician had done so far was discover a soduko with 17 remaining cells and only two solutions. I recently read an article about sudoku in the newspaper. From a mathematical point of view it seemed a lot more complicated than I had expected. It is eg. still unknown to mathematicians how many sudoku challenges there are. Remember here that a true soduku has one and only one solution as mentioned above ! The article mentioned that there was one mathematician who though that you could have a sudoku with 16 remaining cells and a unique solution. It remains to be proven though. I believe the best any mathematician had done so far was discover a soduko with 17 remaining cells and only two solutions.

]]> By: Ellie http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-36506 Ellie Mon, 15 Jan 2007 16:37:25 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-36506 I have implemented an excel macro for this algorithm. Although my removal method is a little different. The problem with step 2 is that it allows for a repeating pattern with respect to column for each sub grid, as can be seen from your example '2 5 8', '3 6 9', '1 4 7' will always be in the same column for each sub grid. I am still looking for an algorith to break that. I have implemented an excel macro for this algorithm. Although my removal method is a little different. The problem with step 2 is that it allows for a repeating pattern with respect to column for each sub grid, as can be seen from your example ’2 5 8′, ’3 6 9′, ’1 4 7′ will always be in the same column for each sub grid. I am still looking for an algorith to break that.

]]> By: joshua http://blog.forret.com/2006/08/a-sudoku-challenge-generator/comment-page-1/#comment-31565 joshua Thu, 04 Jan 2007 14:42:19 +0000 http://blog.forret.com/2006/08/a-sudoku-challenge-generator/#comment-31565 can I use the algorithm in my project? can I use the algorithm in my project?

]]>