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Can anyone help me solve this Sudoku?

I received this Sudoku url from a friend. He says he's solved it up to here, but he's stuck:

http://www.freesudokuhost.com/showsudokuhosting.php?id=20051224213001997

I'm unable to move ahead either. I asked my friends, but no one is able to help.

I'm fairly good with Sudokus, and so is my friend who sent this to me. All I need is just the next step. I can (hopefully) solve it from there.

Thanks,

Elizabeth Daniel.

By Elizabeth Daniel at 2005-12-26 13:18 | LtU Forum | previous forum topic | next forum topic | other blogs | 10530 reads

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Solving sudoku with constraints

Why not let the computer help you? Here are some Oz programs to solve Sudoku puzzles, done this Fall by Russ Abbott and his students in the course CS460 at CalState:

Simple solution

Four other solutions

By Peter Van Roy at Mon, 2005-12-26 15:26 |

This is not an appropriate fo

This is not an appropriate forum for help with Sudoku.

By Ehud Lamm at Mon, 2005-12-26 17:55 |

This Puzzle has no Solution

The reason you can't solve this puzzle is that it has no solution. Maybe the original puzzle was unsolvable or maybe you made an incorrect assertion along the way.

I used my Sudoku solver to confirm this. It might make for an interesting program to find the minimum set of constraints that would need to be removed in order to make the puzzle solvable.

By Kevin Greer at Mon, 2005-12-26 19:47 |

It has a solution

I have a sudoku program on my phone, and it can calculate a solution. My guess is that the solution isn't unique and that a solver that assumes a unique solution might not find one.

By Sjoerd Visscher at Mon, 2005-12-26 21:51 |

A bug

Your solver has a bug. (See the result of your example!)

if ( s[a][b][x][y] == j || s[a][x][c][y] == j || s[x][y][c][d] == j )

should be

if ( s[a][b][x][y] == j || s[a][x][c][y] == j || s[x][b][y][d] == j )

By Sjoerd Visscher at Mon, 2005-12-26 22:28 |

Fixed

Ah, thanks for the fix. When I run it now I get this answer:

 2 3 9 | 5 4 8 | 6 7 1
 4 7 1 | 2 6 9 | 8 5 3
 6 8 5 | 3 7 1 | 4 2 9
-------+-------+-------
 5 1 6 | 7 8 3 | 9 4 2
 8 9 2 | 1 5 4 | 3 6 7
 3 4 7 | 6 9 2 | 1 8 5
-------+-------+-------
 1 6 4 | 9 2 5 | 7 3 8
 7 2 3 | 8 1 6 | 5 9 4
 9 5 8 | 4 3 7 | 2 1 6

By Kevin Greer at Tue, 2005-12-27 00:34 |

Multiple solutions

You could change your program to let it show all possible solutions. (Something like replacing return true with display(); return false)

By Sjoerd Visscher at Tue, 2005-12-27 22:05 |

Correct

Yes, that's what I did first. This even makes the program smaller as I don't need to worry about returning values. The problem with this however was that in cases where there are a lot of solutions it was crashing my browser. I guess that JavaScript really isn't the ideal language for this type of program. I should have written it in Java or C (it is practically identical anyway) but I actually wrote it as an exercise for learning JavaScript (it is my first JS program).

By Kevin Greer at Wed, 2005-12-28 01:47 |