FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in          Games  Calendar Log in to check your private messages    Help for a Learner          Sudoku Programmers Forum Index -> Solving sudoku View previous topic :: View next topic   Author Message dbell Joined: 21 Nov 2009 Posts: 2 : Items Posted: Sat Nov 21, 2009 5:22 pm    Post subject: Help for a Learner I'm just getting into Sudoku solving by working the daily Universal Press puzzle printed in my newspaper. I'm hoping someone can tell me a technique to help me with todays puzzle. Here is the original puzzle: *-----------* |..3|...|..8| |5.4|21.|...| |...|.6.|41.| |---+---+---| |.4.|3..|...| |6.8|4.9|3.1| |...|..5|.9.| |---+---+---| |.76|.5.|...| |...|.94|2.5| |4..|...|1..| *-----------* and my partial solution: *-----------* |..3|947|..8| |5.4|218|.3.| |...|563|41.| |---+---+---| |.4.|3..|...| |6.8|4.9|3.1| |...|..5|.94| |---+---+---| |.76|.5.|.43| |..1|.94|2.5| |4..|.3.|1..| *-----------* Any suggestions would be appreciated. Back to top sudoking Joined: 20 Oct 2009 Posts: 40 : Items Posted: Sat Nov 21, 2009 8:35 pm    Post subject: This will make it easier to read. Code:  *-----------------------*  | . . 3 | 9 4 7 | . . 8 |  | 5 . 4 | 2 1 8 | . 3 . |  | . . . | 5 6 3 | 4 1 . |  |-------+-------+-------|  | . 4 . | 3 . . | . . . |  | 6 . 8 | 4 . 9 | 3 . 1 |  | . . . | . . 5 | . 9 4 |  |-------+-------+-------|  | . 7 6 | . 5 . | . 4 3 |  | . . 1 | . 9 4 | 2 . 5 |  | 4 . . | . 3 . | 1 . . |  *-----------------------* The first step would be to populate the candidates for each cell, like this: Code: +----------------+--------------+----------------+ |   12  126    3 |    9   4   7 |   56   256   8 | |    5   69    4 |    2   1   8 |  679     3 679 | | 2789  289  279 |    5   6   3 |    4     1 279 | +----------------+--------------+----------------+ | 1279    4 2579 |    3 278 126 | 5678 25678 267 | |    6   25    8 |    4  27   9 |    3   257   1 | | 1237  123   27 | 1678 278   5 |  678     9   4 | +----------------+--------------+----------------+ |  289    7    6 |   18   5  12 |   89     4   3 | |   38   38    1 |  678   9   4 |    2   678   5 | |    4 2589  259 |  678   3  26 |    1   678 679 | +----------------+--------------+----------------+ There are several eliminations here. Then it starts to get tricky, requiring forced chains (according to sudoku explainer). Back to top daj95376 Joined: 05 Feb 2006 Posts: 349 : Items Posted: Sat Nov 21, 2009 8:55 pm    Post subject: Re: Help for a Learner dbell wrote: I'm just getting into Sudoku solving by working the daily Universal Press puzzle printed in my newspaper. I'm hoping someone can tell me a technique to help me with todays puzzle. ... Any suggestions would be appreciated. Many newspapers post easy puzzles early in the week and advanced puzzles for Friday and Saturday. That appears to be the case for your puzzle. Code:  +-----------------------+  | . . 3 | . . . | . . 8 |  | 5 . 4 | 2 1 . | . . . |  | . . . | . 6 . | 4 1 . |  |-------+-------+-------|  | . 4 . | 3 . . | . . . |  | 6 . 8 | 4 . 9 | 3 . 1 |  | . . . | . . 5 | . 9 . |  |-------+-------+-------|  | . 7 6 | . 5 . | . . . |  | . . . | . 9 4 | 2 . 5 |  | 4 . . | . . . | 1 . . |  +-----------------------+ Unfortunately, posting only your solved cells doesn't tell us about your eliminations in cells that weren't solved. I'm going to assume that you progressed to this point. Code:  +-----------------------------------------------------------------------+  |  12     126    3      |  9      4      7      |  56     256    8      |  |  5      69     4      |  2      1      8      |  679    3      679    |  |  2789   289    279    |  5      6      3      |  4      1      29     |  |-----------------------+-----------------------+-----------------------|  |  1279   4      2579   |  3      278    16     |  5678   25678  267    |  |  6      25     8      |  4      27     9      |  3      257    1      |  |  1237   123    27     |  16     278    5      |  678    9      4      |  |-----------------------+-----------------------+-----------------------|  |  29     7      6      |  18     5      12     |  89     4      3      |  |  38     38     1      |  67     9      4      |  2      67     5      |  |  4      259    259    |  678    3      26     |  1      678    679    |  +-----------------------------------------------------------------------+  # 71 eliminations remain At this point, I'd suggest using an (advanced) W-Wing pattern. Since you probably aren't familiar with the notation commonly used, I'll describe one way of understanding how it works on this puzzle. Candidate <1> occurs only twice in row 4. Each sees a cell containing <12>. Code: r4c1=1 r1c1=2 r7c1<>2, or r4c6=1 r7c6=2 r7c1<>2 In both cases, r7c1<>2 follows. NOTE: you need to post future questions about puzzles in the Puzzles section. Back to top wapati Joined: 12 Jun 2007 Posts: 622 : Location: Canada Items Posted: Sat Nov 21, 2009 11:50 pm    Post subject: daj95376 wrote: NOTE: you need to post future questions about puzzles in the Puzzles section. Perhaps true. This website might consider changes. If some one comes here with a question about a puzzle should they go to: A: Library>>Puzzles B: Solving Sudoku C: Another website Back to top sudoking Joined: 20 Oct 2009 Posts: 40 : Items Posted: Sun Nov 22, 2009 3:19 pm    Post subject: wapati wrote: C: Another website That should probably be reserved for those that hassle the noobies for posting questions on solving sudoku puzzles in the solving sudoku forum. Back to top m_b_metcalf Joined: 13 Mar 2006 Posts: 210 : Location: Berlin Items Posted: Sun Nov 22, 2009 3:35 pm    Post subject: sudoking wrote: wapati wrote: C: Another website That should probably be reserved for those that hassle the noobies for posting questions on solving sudoku puzzles in the solving sudoku forum. That should probably be reserved for those that hassle the noobies for posting questions on solving sudoku puzzles in the solving sudoku forum of the Programmers' Forum. Regards, Mike Metcalf Back to top dbell Joined: 21 Nov 2009 Posts: 2 : Items Posted: Mon Nov 23, 2009 1:44 am    Post subject: I apologize for posting my question in the wrong forum. I do appreciate the responses, however. I think this puzzle is beyond my level of comprehension at this time but I'll continue trying to learn some of these higher level techniques. Thanks. Back to top tarek Joined: 31 Dec 2005 Posts: 153 : Location: London, UK Items Posted: Mon Nov 23, 2009 3:57 pm    Post subject: you are also advised to visit http://www.sudoku.com/boards/index.php for advice regarding solving puzzles from an audience not involved with programming - Or from a player not wearing a programmers hat - tarek Back to top alb123456 Joined: 05 Dec 2009 Posts: 1 : Items Posted: Sat Dec 05, 2009 4:34 am    Post subject: alb123456 hello Back to top Adak Joined: 27 Feb 2008 Posts: 87 : Items Posted: Sat Dec 05, 2009 2:47 pm    Post subject: Welcome to the forum, alb. Back to top samuilov Joined: 06 Feb 2010 Posts: 2 : Items Posted: Sat Feb 06, 2010 6:17 pm    Post subject: i like it here hey guys i just wanna congratulate this community i am also a sudoku fan and i like solving puzzles Back to top samuilov Joined: 06 Feb 2010 Posts: 2 : Items Posted: Sat Feb 06, 2010 6:18 pm    Post subject: aa aaaa Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         Sudoku Programmers Forum Index -> Solving sudoku All times are GMT Page 1 of 1   Jump to: Select a forum Sudoku----------------Solving sudokuSetting sudokuProgramming sudokuThe mathematics of sudokuExotic sudoku Library----------------PuzzlesSoftwareSudoku elsewhere Not sudoku----------------Random thoughtsForum feedback  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum   Powered by phpBB © 2001, 2005 phpBB Group Igloo Theme Version 1.0 :: Created By: Andrew Charron