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 2009-01-15, 16:25 #1 mwxdbcr     Jan 2009 5 Posts Sodyoutoo (a.k.a. Sudoku) ╮(╯▽╰)╭ 哎，数独啊。玩过米啊~~~~ ★★★★0001--0010 3 2 0 0 0 0 0 4 6 0 0 5 0 0 0 9 0 0 0 8 9 2 0 4 3 1 0 0 0 7 0 9 0 0 0 0 8 3 0 0 0 0 0 2 9 0 0 2 0 4 0 0 0 0 0 9 3 4 0 6 2 7 0 0 0 8 0 0 0 4 0 0 7 4 0 0 0 0 0 9 8 0 4 0 9 0 0 0 0 0 9 0 5 0 7 0 0 0 3 0 3 0 0 0 4 6 0 9 0 2 0 3 0 0 0 5 0 0 0 9 1 0 5 7 0 0 0 5 0 0 0 2 0 9 0 4 0 8 5 0 0 0 3 0 5 0 0 0 6 0 9 0 4 0 0 0 0 0 9 0 8 0 0 1 0 6 0 9 0 3 0 0 0 6 0 3 0 9 0 0 0 3 0 0 8 0 0 5 0 3 2 0 0 4 0 0 8 5 0 0 0 5 0 7 0 0 0 9 0 0 0 0 0 0 0 7 0 8 0 0 5 0 0 9 0 0 0 1 0 9 0 8 0 0 0 9 0 8 0 2 0 6 0 2 0 0 0 0 0 0 0 5 0 9 6 0 0 0 1 2 0 0 0 0 8 0 2 0 0 0 0 3 0 9 0 8 0 4 0 0 0 9 0 7 0 2 0 0 0 8 0 5 0 6 0 7 0 0 0 8 3 0 7 9 0 0 0 0 4 0 0 0 5 0 0 9 2 0 0 0 0 0 8 7 0 0 0 3 1 6 0 0 0 1 6 0 0 0 0 0 2 9 0 0 0 9 8 2 0 0 0 0 1 5 0 0 0 8 9 0 0 0 0 0 9 0 0 0 0 0 9 7 0 0 0 2 6 0 0 0 0 1 4 9 0 0 0 9 2 0 0 0 0 0 7 4 0 0 0 2 7 5 0 0 0 2 0 0 9 4 1 0 0 6 0 0 0 7 0 3 0 0 0 0 0 7 0 0 0 9 0 0 7 2 0 5 0 9 0 4 3 3 0 0 0 0 0 0 0 5 8 5 0 4 0 2 0 6 7 0 0 2 0 0 0 3 0 0 0 0 0 2 0 6 0 0 0 4 0 0 3 8 7 0 0 2 0 0 8 4 0 0 7 9 6 0 0 7 0 0 9 0 0 0 0 9 0 0 2 0 0 0 5 7 0 0 9 0 2 0 1 0 0 6 0 0 0 0 9 0 0 9 0 0 7 0 3 0 2 0 0 7 0 0 9 0 0 0 2 0 0 4 0 0 6 0 0 0 0 0 9 2 0 0 8 7 4 1 8 0 0 9 0 0 6 4 0 0 5 0 1 0 0 0 0 3 0 0 0 0 0 1 2 0 0 1 0 2 0 9 0 0 0 0 0 0 0 4 0 0 0 3 0 5 0 8 0 7 0 0 0 2 0 0 0 0 0 5 8 0 0 0 4 0 8 0 0 0 0 8 7 0 0 2 0 0 1 6 2 7 0 0 0 0 0 0 0 3 0 8 0 7 0 9 0 0 0 0 0 0 3 1 0 0 2 0 4 0 7 0 6 2 0 0 0 0 0 0 0 0 7 8 0 0 1 0 2 0 5 4 0 0 0 0 0 0 2 7 0 0 9 7 0 6 0 5 0 3 0 0 9 5 0 0 0 0 0 0 0 0 0 4 2 0 0 0 0 0 0 0 6 8 0 0 4 1 0 0 0 0 0 0 0 8 2 0 0 2 0 0 1 0 0 0 5 8 3 0 0 2 9 0 7 6 0 9 0 0 3 0 0 0 8 0 0 0 0 0 0 7 8 0 0 0 8 7 0 0 5 9 0 0 0 2 9 0 0 0 0 0
2009-01-15, 16:43   #2
10metreh

Nov 2008

2·33·43 Posts

Quote:
 Originally Posted by mwxdbcr ╮(╯▽╰)╭ 哎，数独啊。玩过米啊~~~~ ★★★★0001--0010 3 2 0 0 0 0 0 4 6 0 0 5 0 0 0 9 0 0 0 8 9 2 0 4 3 1 0 0 0 7 0 9 0 0 0 0 8 3 0 0 0 0 0 2 9 0 0 2 0 4 0 0 0 0 0 9 3 4 0 6 2 7 0 0 0 8 0 0 0 4 0 0 7 4 0 0 0 0 0 9 8 0 4 0 9 0 0 0 0 0 9 0 5 0 7 0 0 0 3 0 3 0 0 0 4 6 0 9 0 2 0 3 0 0 0 5 0 0 0 9 1 0 5 7 0 0 0 5 0 0 0 2 0 9 0 4 0 8 5 0 0 0 3 0 5 0 0 0 6 0 9 0 4 0 0 0 0 0 9 0 8 0 0 1 0 6 0 9 0 3 0 0 0 6 0 3 0 9 0 0 0 3 0 0 8 0 0 5 0 3 2 0 0 4 0 0 8 5 0 0 0 5 0 7 0 0 0 9 0 0 0 0 0 0 0 7 0 8 0 0 5 0 0 9 0 0 0 1 0 9 0 8 0 0 0 9 0 8 0 2 0 6 0 2 0 0 0 0 0 0 0 5 0 9 6 0 0 0 1 2 0 0 0 0 8 0 2 0 0 0 0 3 0 9 0 8 0 4 0 0 0 9 0 7 0 2 0 0 0 8 0 5 0 6 0 7 0 0 0 8 3 0 7 9 0 0 0 0 4 0 0 0 5 0 0 9 2 0 0 0 0 0 8 7 0 0 0 3 1 6 0 0 0 1 6 0 0 0 0 0 2 9 0 0 0 9 8 2 0 0 0 0 1 5 0 0 0 8 9 0 0 0 0 0 9 0 0 0 0 0 9 7 0 0 0 2 6 0 0 0 0 1 4 9 0 0 0 9 2 0 0 0 0 0 7 4 0 0 0 2 7 5 0 0 0 2 0 0 9 4 1 0 0 6 0 0 0 7 0 3 0 0 0 0 0 7 0 0 0 9 0 0 7 2 0 5 0 9 0 4 3 3 0 0 0 0 0 0 0 5 8 5 0 4 0 2 0 6 7 0 0 2 0 0 0 3 0 0 0 0 0 2 0 6 0 0 0 4 0 0 3 8 7 0 0 2 0 0 8 4 0 0 7 9 6 0 0 7 0 0 9 0 0 0 0 9 0 0 2 0 0 0 5 7 0 0 9 0 2 0 1 0 0 6 0 0 0 0 9 0 0 9 0 0 7 0 3 0 2 0 0 7 0 0 9 0 0 0 2 0 0 4 0 0 6 0 0 0 0 0 9 2 0 0 8 7 4 1 8 0 0 9 0 0 6 4 0 0 5 0 1 0 0 0 0 3 0 0 0 0 0 1 2 0 0 1 0 2 0 9 0 0 0 0 0 0 0 4 0 0 0 3 0 5 0 8 0 7 0 0 0 2 0 0 0 0 0 5 8 0 0 0 4 0 8 0 0 0 0 8 7 0 0 2 0 0 1 6 2 7 0 0 0 0 0 0 0 3 0 8 0 7 0 9 0 0 0 0 0 0 3 1 0 0 2 0 4 0 7 0 6 2 0 0 0 0 0 0 0 0 7 8 0 0 1 0 2 0 5 4 0 0 0 0 0 0 2 7 0 0 9 7 0 6 0 5 0 3 0 0 9 5 0 0 0 0 0 0 0 0 0 4 2 0 0 0 0 0 0 0 6 8 0 0 4 1 0 0 0 0 0 0 0 8 2 0 0 2 0 0 1 0 0 0 5 8 3 0 0 2 9 0 7 6 0 9 0 0 3 0 0 0 8 0 0 0 0 0 0 7 8 0 0 0 8 7 0 0 5 9 0 0 0 2 9 0 0 0 0 0
This forum is not a place for sudoku puzzles. There are generators on the Internet and solvers as well.

Solution to the first puzzle:

Code:
321978546
475631982
689254317
517892634
834165729
962347851
193486275
258719463
746523198

Last fiddled with by 10metreh on 2009-01-15 at 16:50

2009-01-15, 17:06   #3
petrw1
1976 Toyota Corona years forever!

"Wayne"
Nov 2006

52·211 Posts

Quote:
 Originally Posted by 10metreh There are generators on the Internet and solvers as well.
This is the best one I have come across:
www.scanraid.com/sudoku.htm

It not only solves but it also shows you each step and explains the techniques it is using.

2009-01-15, 17:41   #4
10metreh

Nov 2008

2·33·43 Posts

Quote:
 Originally Posted by petrw1 This is the best one I have come across: www.scanraid.com/sudoku.htm It not only solves but it also shows you each step and explains the techniques it is using.
Yeah, that's the one I used to solve the first one.

The second:

Code:
246913875
915678243
837254619
721396458
389145762
654782391
498527136
573861924
162439587
The first two only needed singles. The third needed a naked triple:

Code:
514679238
876235941
239184756
327941685
148567329
965328417
482756193
651493872
793812564
As did No. 4:

Code:
247631895
896754123
351892764
735928641
619473258
482516379
568347912
174289536
923165487
No. 5 needed pointing pairs:

Code:
259316748
168457329
734982156
315624897
682791435
497538261
573149682
921863574
846275913
And no. 6 (naked pairs):

Code:
235941786
948763521
167825934
726519843
314678295
859432167
682154379
573296418
491387652

Last fiddled with by 10metreh on 2009-01-15 at 18:12

 2009-01-24, 01:31 #5 biwema     Mar 2004 3·127 Posts Some Sudoku can be quite tricky. The following example has exactly one solution, but i am not sure if there is a solving strategy (except brute force). Even the sudoku solver (mentioned above) failed. Code: 12.34.5.. 3....6... .54....3. 24....3.7 ..5.....2 ...428... 4..6..72. .1......6 ...9..... Does someone know a strategy, that can solve this one? Last fiddled with by biwema on 2009-01-24 at 01:32 Reason: minor corrections
2009-01-24, 05:07   #6
petrw1
1976 Toyota Corona years forever!

"Wayne"
Nov 2006

52×211 Posts

Quote:
 Originally Posted by biwema Some Sudoku can be quite tricky. The following example has exactly one solution, but i am not sure if there is a solving strategy (except brute force). Even the sudoku solver (mentioned above) failed. Code: 12.34.5.. 3....6... .54....3. 24....3.7 ..5.....2 ...428... 4..6..72. .1......6 ...9..... Does someone know a strategy, that can solve this one?
Hmmm I've never had that site fail before....

2009-01-24, 06:02   #7
jrk

May 2008

109510 Posts

Quote:
 Originally Posted by biwema Some Sudoku can be quite tricky. The following example has exactly one solution, but i am not sure if there is a solving strategy (except brute force). Even the sudoku solver (mentioned above) failed. Code: 12.34.5.. 3....6... .54....3. 24....3.7 ..5.....2 ...428... 4..6..72. .1......6 ...9..... Does someone know a strategy, that can solve this one?
Code:
126347598
398156274
754892631
241569387
985713462
673428159
439681725
817235946
562974813
I used KSudoku's solver.

2009-01-24, 06:29   #8
jrk

May 2008

3×5×73 Posts

KSudoku's solver is basically an optimized bruteforce. Here's the description of it on http://ksudoku.sourceforge.net/2.htm

Quote:
 SudokuSolve() Check puzzle validity For every cell see what's linked and place a flag if it can contain each number or not Find the cell with the lowest acceptable numbers nn Find the strongly connected subgraph that has the least candidates (lc) for a value (deprecated, not worth) Select n as the lowest between lc and nn if (n lower than 0) error if (n==1) write down and new SudokuSolve() call if (n greater than 1) recursive fork with all possibilities

 2009-01-24, 07:44 #9 10metreh     Nov 2008 2·33·43 Posts Yes - I think an improvement to the scanraid solver would be to add guessing after all its logical strategies.
 2009-01-24, 08:58 #10 henryzz Just call me Henry     "David" Sep 2007 Liverpool (GMT/BST) 37×163 Posts i would suggest biwema that you send some feedback about this puzzle i suspect he would want examples that it cant solve so he can make it better
 2009-01-24, 23:55 #11 biwema     Mar 2004 3·127 Posts I think i will not send in that example. I also found it some time ago somewhere else (cannot remember exactly), so i do not have the copyrights. I think i am not the right person as i have not much experience with sudokus. I am sure there are also sudoku forums and communities that have many members who are experts and know problems like this. It seems as id there are examples that are not solvable using logic strategies and need recursion or brute force. If someone would like to send in the example, feel free to do so.

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