Comments on: The Sudoku Infection http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/ Utterly random, incoherent and disjointed rants and ramblings... Sat, 17 May 2008 03:50:15 +0000 http://wordpress.org/?v=2.0.5 by: Shannon http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8631 Mon, 31 Mar 2008 08:27:05 +0000 http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8631 Tanks for the pencil tip, I'm not a huge fan of sudoku but I do it sometimes and it might help make my life easier. Tanks for the pencil tip, I’m not a huge fan of sudoku but I do it sometimes and it might help make my life easier.

]]> by: Matt` http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8625 Sat, 29 Mar 2008 15:07:28 +0000 http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8625 I'm sure I had some other trick to bust out when the going got really tough... can't remember what it was though. I’m sure I had some other trick to bust out when the going got really tough… can’t remember what it was though.

]]> by: ths http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8622 Fri, 28 Mar 2008 14:14:48 +0000 http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8622 german c't magazine had a very nice article in issue 20/2006, and the author discussed the mathematics required and the backtracking algorithm he used quite nicely. The article came with a nice sudoku software for playing and solving, written in C#, and it requires .net 2.0+. german c’t magazine had a very nice article in issue 20/2006, and the author discussed the mathematics required and the backtracking algorithm he used quite nicely. The article came with a nice sudoku software for playing and solving, written in C#, and it requires .net 2.0+.

]]> by: Luke Maciak http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8618 Fri, 28 Mar 2008 05:27:46 +0000 http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8618 <strong>@Dax</strong> - yeah, these things do come up. They never did for me though. Also, I didn't know about Kakuro. It's like a crossword puzzle... Only without words. Heh! @Dax - yeah, these things do come up. They never did for me though.

Also, I didn’t know about Kakuro. It’s like a crossword puzzle… Only without words. Heh!

]]> by: Luke Maciak http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8616 Thu, 27 Mar 2008 19:09:07 +0000 http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8616 <strong>@Matt`</strong> - Ah, good suggestion. I didn't think of that. Thanks - this actually improves the human based algorithm a bit. :) @Matt` - Ah, good suggestion. I didn’t think of that. Thanks - this actually improves the human based algorithm a bit. )

]]> by: Dax http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8615 Thu, 27 Mar 2008 18:46:41 +0000 http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8615 I actually ran into a "graph problem" in my work once. I boiled the problem I was trying to solve down to an issue of <a href="http://en.wikipedia.org/wiki/Topological_sort" rel="nofollow">topological sorting</a>. Funny thing was that I didn't need to implement a graph to accomplish it. As far as Sudoku goes, I'm not much of a fan. I prefer to solve <a href="http://en.wikipedia.org/wiki/Kakuro" rel="nofollow">Kakuro puzzles</a>. I actually ran into a “graph problem” in my work once. I boiled the problem I was trying to solve down to an issue of topological sorting. Funny thing was that I didn’t need to implement a graph to accomplish it.

As far as Sudoku goes, I’m not much of a fan. I prefer to solve Kakuro puzzles.

]]> by: Matt` http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8614 Thu, 27 Mar 2008 18:22:06 +0000 http://www.terminally-incoherent.com/blog/2008/03/27/the-sudoku-infection/#comment-8614 I used to use the "pencil in tiny little numbers then work by elimination" method. One thing that might need to be considered that you didn't cover up top is the effect of pairs/triples. If 2 boxes in one column have the same 2 numbers left (and only those 2), then that pair of numbers must be in that pair of boxes, and so those numbers can be eliminated from the rest of the line. You can also remove all other numbers from a box if its one of a pair and there's nowhere else for the 2 numbers to go, which may mean one other box is left as the only possibility for one of the numbers you removed. Some of the harder ones will require you to make a choice somewhere and follow it through, while being prepared to go back to that point if it turns out that was wrong, some will have multiple dead ends and possible trails to follow.. I don't like those ones, feels too fuzzy and not logic-y enough. The Times' puzzles are all pure logic though I used to use the “pencil in tiny little numbers then work by elimination” method. One thing that might need to be considered that you didn’t cover up top is the effect of pairs/triples.

If 2 boxes in one column have the same 2 numbers left (and only those 2), then that pair of numbers must be in that pair of boxes, and so those numbers can be eliminated from the rest of the line.

You can also remove all other numbers from a box if its one of a pair and there’s nowhere else for the 2 numbers to go, which may mean one other box is left as the only possibility for one of the numbers you removed.

Some of the harder ones will require you to make a choice somewhere and follow it through, while being prepared to go back to that point if it turns out that was wrong, some will have multiple dead ends and possible trails to follow.. I don’t like those ones, feels too fuzzy and not logic-y enough. The Times’ puzzles are all pure logic though

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