FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in          Games  Calendar Log in to check your private messages    what is the hardest known suduko ? Goto page Previous  1, 2, 3 ... , 11, 12, 13  Next          Sudoku Programmers Forum Index -> Solving sudoku View previous topic :: View next topic   Author Message JPF Joined: 05 Dec 2005 Posts: 29 : Location: Paris Items Posted: Fri Jun 08, 2007 10:00 pm    Post subject: rickhev1 wrote: Here is the hardest sudoku I have encountered. It is by JPF and is rated 11.4 by SE. Mike Metcalf's above is the next hardest one I know of. Thanks rickhev1. If you want to know more about hard sudokus you must have a look at some threads : The hardest sudokus How regular is to generate sudoku with difficulty 9+ SE? You can also find a list made by gsf with different rating systems here. In April, I posted this puzzle, known as the Easter Monster (SE=11.4) and gsfr=99408 : Code:  1 . . | . . . | . . 2  . 9 . | 4 . . | . 5 .  . . 6 | . . . | 7 . . -------+-------+-------  . 5 . | 9 . 3 | . . .  . . . | . 7 . | . . .  . . . | 8 5 . | . 4 . -------+-------+-------  7 . . | . . . | 6 . .  . 3 . | . . 9 | . 8 .  . . 2 | . . . | . . 1 JPF Back to top latian Joined: 08 Jan 2008 Posts: 5 : Items Posted: Tue Jan 08, 2008 2:46 pm    Post subject: Re: soduko solver humbertoldi wrote: The logical methods implemented are rather simple (no X-Wing, pairs and other fancy stuff). If these methods alone are not sufficient, the program solves by (recursive) guessing. There are many available solvers. Pure "recursive guessing" works, but this is not the point here. Back to top dodo Joined: 11 Jul 2005 Posts: 5 : Items Posted: Sun Feb 17, 2008 12:01 pm    Post subject: A local newspaper published (perhaps by mistake) the following: Code: 1.4|.5.|.8. 3.8|.6.|2.. .9.|8..|..7 ----------- 6..|5..|..4 ..2|.4.|7.. 7..|..1|..3 ----------- 4..|..6|.9. ..7|.9.|1.8 .5.|.3.|4.6 After a few steps I arrived at Code: 124|.5.|689 378|.6.|2.. 596|8..|3.7 ----------- 6..|5..|..4 ..2|.4.|7.. 745|..1|..3 ----------- 4..|..6|592 267|495|138 .5.|.3.|476 but neither me nor the Simple Sudoku program can proceed further. Backtrack shows this as "the" solution (I believe there is no other, but I'm not sure): Code: 124|753|689 378|964|251 596|812|347 ----------- 639|527|814 812|349|765 745|681|923 ----------- 483|176|592 267|495|138 951|238|476 Any hint of solving it without backtracking? Back to top tarek Joined: 31 Dec 2005 Posts: 153 : Location: London, UK Items Posted: Sun Feb 17, 2008 12:16 pm    Post subject: dodo wrote: Any hint of solving it without backtracking? Code: *--------------------------------------------------------* | 1     2     4    | 37    5     37   | 6     8     9    | | 3     7     8    |%19    6    #49   | 2     145   15   | | 5     9     6    | 8     12   #24   | 3     14    7    | |------------------+------------------+------------------| | 6     138   139  | 5     278   23789| 89    12    4    | | 89    138   2    | 369   4     389  | 7     156   15   | | 7     4     5    | 269   28    1    | 89    26    3    | |------------------+------------------+------------------| | 4     138   13   | 17    178   6    | 5     9     2    | | 2     6     7    | 4     9     5    | 1     3     8    | | 89    5     19   |%12    3    -28   | 4     7     6    | *--------------------------------------------------------* Eliminating 2 from r9c6(ALS-XZ A=129(%) in r29c4 B=249(#) in r23c6 x=9 z=2) if the most difficult sudoku is a 10, this would be a .001 tarek Back to top tarek Joined: 31 Dec 2005 Posts: 153 : Location: London, UK Items Posted: Sun Feb 17, 2008 3:18 pm    Post subject: I just noticed that this thread needs an update......... I will be posting a list of puzzles with its original poster shortly. This list on one side has the solver program & on the other the puzzle which rates highst according to it.... My thoughts for the moment are : gsf's sudoku q1 option, Sudoku explainer 1.2.1, SuexratX & probably ravel's minimal steps (RMS), there have been contributions from Obi-Wahn, Champagne & others with their solvers. this could be added to the list. tarek Back to top daj95376 Joined: 05 Feb 2006 Posts: 349 : Items Posted: Sun Feb 17, 2008 7:57 pm    Post subject: There is a Unique Rectangle Type 4 for candidates 15 => [r25c8]<>1, but it doesn't help There is a W-Wing/Semi-Remote Naked Pair/Y-Wing Styles between cells [r6c5],[r9c6] with strong link [r3c5]=2=[r3c6] that results in three eliminations in 8, the PM cracks at this point Code: +--------------------------------------------------------------------+ |  1      2      4     |  37     5      37    |  6      8      9     | |  3      7      8     |  19     6      49    |  2      45-1   15    | |  5      9      6     |  8      12-----24    |  3      14     7     | |----------------------+----------------------+----------------------| |  6      138    139   |  5      278    379-8 |  89     12     4     | |  89     138    2     |  369    4      39-8  |  7      56-1   15    | |  7      4      5     |  269   *28     1     |  89     26     3     | |----------------------+----------------------+----------------------| |  4      138    13    |  17     17-8   6     |  5      9      2     | |  2      6      7     |  4      9      5     |  1      3      8     | |  89     5      19    |  12     3     *28    |  4      7      6     | +--------------------------------------------------------------------+ Back to top hobiwan Joined: 11 Feb 2008 Posts: 83 : Items Posted: Mon Feb 18, 2008 10:07 am    Post subject: There are also some XY-Chains, that solve the puzzle, for example: XY-Chain candidate 9: [r2c4]-1-[r3c5]-2-[r6c5]-8-[r6c7] => [r6c4]<>9, puzzle solved XY-Chain candidate 1: [r2c4]-9-[r2c6]-4-[r3c6]-2-[r9c6]-8-[r9c1]-9-[r9c3] => [r9c4]<>1, puzzle solved XY-Chain candidate 8: [r6c5]-2-[r3c5]-1-[r3c8]-4-[r3c6]-2-[r9c6] => [r45c6]<>8, [r7c5]<>8, puzzle solved Back to top tarek Joined: 31 Dec 2005 Posts: 153 : Location: London, UK Items Posted: Thu Feb 21, 2008 7:38 pm    Post subject: Here is an up-to-date list of the hardest puzzles according to some solver programs...... Additions/corrections are most welcome. Hardest Sudokus according to various solver programs: gsf's sudoku q1 (rating) 1.......2.9.4...5...6...7...5.9.3.......7.......85..4.7.....6...3...9.8...2.....1 JPF Easter Monster 99408 gsf's sudoku q1 (Processing time) ..1..4.......6.3.5...9.....8.....7.3.......285...7.6..3...8...6..92......4...1... tarek tarek071223170000-052 4m19s@2Ghz Nicolas Juillerat's Sudoku explainer 1.2.1 .......39.....1..5..3.5.8....8.9...6.7...2...1..4.......9.8..5..2....6..4..7..... tarek golden nugget 11.9 dukuso's suexrat9 .2.4.37.........32........4.4.2...7.8...5.........1...5.....9...3.9....7..1..86.. coloin col-02-08-071 4483 dukuso's suexratt .......39.....1..5..3.5.8....8.9...6.7...2...1..4.......9.8..5..2....6..4..7..... tarek golden nugget 2141 RMS .....1.2.3...4.5.....6....7..2.....1.8..9..3.4.....8..5....2....9..3.4....67..... Ocean Ocean's New Year's present for RW 24 Obi-Wahn's solver 1.......2.9.4...5...6...7...5.3.4.......6........58.4...2...6...3...9.8.7.......1 coloin coloin-04/13-1414 1 Star - 7 Jellies - 27 Swords Champagne's solver (Processing time) .......39.....1..5..3.5.8....8.9...6.7...2...1..4.......9.8..5..2....6..4..7..... tarek golden nugget 96s250 tarek Back to top witch hunter robin Joined: 09 Oct 2008 Posts: 2 : Items Posted: Thu Oct 09, 2008 2:59 am    Post subject: Personally I find the 25x25 the most challenging. Yes, I have solved them on my own. Back to top MacroSudoku Joined: 06 Nov 2008 Posts: 4 : Items Posted: Thu Nov 06, 2008 2:38 pm    Post subject: Regarding the: gsf's sudoku q1 (Processing time) ..1..4.......6.3.5...9.....8.....7.3.......285...7.6..3...8...6..92......4...1... tarek tarek071223170000-052 4m19s@2Ghz My solver takes only 1 015 milliseconds (which is more or less 1 second) to solve it, with a intel celeron M 1.5GHz... Does it mean that my solver (MacroSudoku) is quicker than the one used to rate the above Sudoku? Back to top Mauricio Joined: 22 Mar 2006 Posts: 21 : Items Posted: Thu Nov 06, 2008 5:16 pm    Post subject: Solving and rating are 2 different things. Back to top tarek Joined: 31 Dec 2005 Posts: 153 : Location: London, UK Items Posted: Thu Nov 06, 2008 5:39 pm    Post subject: MacroSudoku wrote: My solver takes only 1 015 milliseconds (which is more or less 1 second) to solve it, with a intel celeron M 1.5GHz... Does it mean that my solver (MacroSudoku) is quicker than the one used to rate the above Sudoku? That is the quoted figure for q1 (a rating algorithm in gsf's sudoku) Processing time. tarek Back to top MacroSudoku Joined: 06 Nov 2008 Posts: 4 : Items Posted: Thu Nov 06, 2008 5:45 pm    Post subject: Ok, thanks for the info. But does it mean that my solver is pretty quick (i.e quicker than the one used by tarek), even though I made it with visual basic (which is not really known for its rapidity)? Also, if my solver use human-solving techniques, why can't we say that solving and rating are related? I mean, the macro and a human would more or less apply the same solving techniques, so it looks to me that they should be related in some way, no? Back to top MacroSudoku Joined: 06 Nov 2008 Posts: 4 : Items Posted: Thu Nov 06, 2008 5:46 pm    Post subject: Ok sorry, i've got my answer now... and it seems that our posts were sent at more or less the same time Back to top ququman Joined: 30 Jun 2006 Posts: 4 : Items Posted: Thu May 14, 2009 2:19 am    Post subject: I would like to submit a puzzle that is harder than the Easter Monster. I would like your opinions on this puzzle: 090030006 004500000 800001000 020090300 006000002 500000070 000700500 000008010 003060004 Let me know what you think. 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