FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in          Games  Calendar Log in to check your private messages    View/download C code for Random Sudoku Generator          Sudoku Programmers Forum Index -> Programming sudoku View previous topic :: View next topic   Author Message Lunatic Joined: 11 Mar 2007 Posts: 166 : Location: Ghent - Belgium Items Posted: Fri Nov 21, 2008 11:36 pm    Post subject: View/download C code for Random Sudoku Generator For anyone interrested, i've translated my VisualBasic code from my own sudoku generator to C code. It's a stripped down version who just generates a random solution and then turns it into an 180° rotational Sudoku with one unique solution. The code can be viewed/downloaded with this URL: http://users.pandora.be/mpq/sudoku/random_sudoku_generator.c _________________ Marc ~~~<><~~~<><~~~<><~~~<><~~~ Back to top cardinal Joined: 08 Apr 2006 Posts: 40 : Items Posted: Wed Dec 10, 2008 7:39 am    Post subject: Why used naked single and not hidden single ? from my experience, hidden singles and brute force are enough to solve any puzzle in reasonable amount of time and, i loop indefinitely removing clues when generating random puzzles :lol: Back to top Lunatic Joined: 11 Mar 2007 Posts: 166 : Location: Ghent - Belgium Items Posted: Wed Dec 10, 2008 11:28 am    Post subject: cardinal wrote: Why used naked single and not hidden single ? The way i wrote the code, happens to be easier to spot naked singles, rather than hidden singles. I did tried hidden singles, but it slowed down the overall performance. One could use more/better bitwise arrays to make it easier to spot hidden singles to gain speed. The code i published is merely an example, anyone may use it and/or improve it. _________________ Marc ~~~<><~~~<><~~~<><~~~<><~~~ Back to top cardinal Joined: 08 Apr 2006 Posts: 40 : Items Posted: Wed Dec 10, 2008 8:48 pm    Post subject: yes you are right. the speed is important :) try this animal : ......... .4....... ...6..8.. ...9..... .....85.. ...2..... .......34 .69....2. 2.......6 Back to top tarek Joined: 31 Dec 2005 Posts: 153 : Location: London, UK Items Posted: Wed Dec 10, 2008 9:00 pm    Post subject: cardinal wrote: try this animal : ......... .4....... ...6..8.. ...9..... .....85.. ...2..... .......34 .69....2. 2.......6 That animal has no 1s & no 7s tarek Back to top Lunatic Joined: 11 Mar 2007 Posts: 166 : Location: Ghent - Belgium Items Posted: Wed Dec 10, 2008 10:10 pm    Post subject: cardinal wrote: yes you are right. the speed is important try this animal : ......... .4....... ...6..8.. ...9..... .....85.. ...2..... .......34 .69....2. 2.......6 My code is the code for a generator, not a uniqueness tester/solver. However, there's a uniqueness tester implemented, so you can easely transform it into a tester. _________________ Marc ~~~<><~~~<><~~~<><~~~<><~~~ Back to top cardinal Joined: 08 Apr 2006 Posts: 40 : Items Posted: Thu Dec 11, 2008 12:20 am    Post subject: when i'm trying to make a truly random generator, i step into some bad situations :lol: for example, solving top 1465 is no problem, but randomness, is different thing, because strange puzzles appear tarek, is there some rule that says something about too many missing digits ? because i'd like some inside information Back to top cardinal Joined: 08 Apr 2006 Posts: 40 : Items Posted: Thu Dec 11, 2008 1:37 am    Post subject: here's another dangerous animal : ...6...7. ...4.5... ...7..... 9.....5.. ...5.7... ....4.... 65....417 .4....... ......... this one blocks sudocue for 2-3 seconds Back to top m_b_metcalf Joined: 13 Mar 2006 Posts: 210 : Location: Berlin Items Posted: Thu Dec 11, 2008 6:19 am    Post subject: cardinal wrote: is there some rule that says something about too many missing digits ? because i'd like some inside information. A valid sudoku's clues must contain at least 8 distinct values, otherwise it certainly has multiple values. Consider a puzzle with no 8s and no 9s. In any solution grid it will be possible to interchange all the 8s with all the 9s, producing a second solution independent of the initial clues. Regards, Mike Metcalf Back to top cardinal Joined: 08 Apr 2006 Posts: 40 : Items Posted: Thu Dec 11, 2008 7:24 am    Post subject: thank you, but also it can have no solution :) so, i have to backtrack it anyway :( to tell if has multiple or no solution or there is a faster way ? Back to top m_b_metcalf Joined: 13 Mar 2006 Posts: 210 : Location: Berlin Items Posted: Thu Dec 11, 2008 8:20 am    Post subject: cardinal wrote: thank you, but also it can have no solution so, i have to backtrack it anyway to tell if has multiple or no solution or there is a faster way ? Yes. 1) If, in any row/column/box, a given value appears neither as a clue nor as a candidate, the puzzle has no solution. 2) If, in any cell, there is neither a clue nor a candidate, the puzzle has zero solutions. 3) If, in any cell, n (n > 1) values appear and they appear only once in the row/column/box, then they are competing for that cell implying a deadlock and so zero solutions. (Limiting to n to 2 covers the vast majority of cases.) For multiple solutions, yes you have to count, but you can stop the count at two. HTH Mike Metcalf Back to top cardinal Joined: 08 Apr 2006 Posts: 40 : Items Posted: Thu Dec 11, 2008 1:53 pm    Post subject: ......3.. ....3.4.6 ......2.. ...5..6.. .4....... .7...9... ...19.... 126.83... ......... Back to top m_b_metcalf Joined: 13 Mar 2006 Posts: 210 : Location: Berlin Items Posted: Thu Dec 11, 2008 2:59 pm    Post subject: cardinal wrote: ......3.. ....3.4.6 ......2.. ...5..6.. .4....... .7...9... ...19.... 126.83... ......... Please don't post on both the Players' and the Programmers' Fora. Thanks, Mike Metcalf Back to top cardinal Joined: 08 Apr 2006 Posts: 40 : Items Posted: Thu Dec 11, 2008 3:14 pm    Post subject: huh ? why ? OK, if you say so :D what about the puzzle ? you still need to backtrack it or you know an easy way out ? thx Back to top hobiwan Joined: 11 Feb 2008 Posts: 83 : Items Posted: Fri Dec 12, 2008 6:26 am    Post subject: m_b_metcalf wrote: Please don't post on both the Players' and the Programmers' Fora. cardinal wrote: huh ? why ? Because many people follow both forums. And just for clarity: Please don't post the same puzzle on both forums. 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