Solved Sudoku incorrect on custom grid

[LiquidDeath911]

I created an empty grid and added all the numbers where they needed to be. The solved grid was incorrect.

Here is the code I ran:

Clear-Host

Import-Module -Name PS-Sudoku

$grid = GenerateGrid -Difficulty Empty $grid.Item(0) = ('-','3','9','-','-','4','-','-','-') $grid.Item(1) = ('1','-','-','-','-','-','5','-','-') $grid.Item(2) = ('-','-','-','2','7','-','-','-','-') $grid.Item(3) = ('8','-','4','-','-','-','-','-','1') $grid.Item(4) = ('-','-','5','-','-','-','-','9','8') $grid.Item(5) = ('9','-','-','-','6','2','7','4','5') $grid.Item(6) = ('-','-','2','6','-','9','8','5','-') $grid.Item(7) = ('6','-','-','-','-','-','-','-','-') $grid.Item(8) = ('-','9','-','-','2','-','-','1','3')

SolveSudoku -SudokuGrid $grid PrintGrid -SudokuGrid $grid

Here is the solved grid that was printed out:

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

You can see in row 8 that there are two 6s. One of those 6s was already present in the original grid. Let me know if you would like any more information on this issue.

[DavisHenckel]

Hey there! Thanks for reporting this. I'll take a look at it and see if I can figure out where that went wrong.

[DavisHenckel]

@LiquidDeath911 Thanks again for reporting this. I verified that the code you displayed does produce an error in the output.

The main thing I noticed was in your code you are initializing the numbers with ' '. I believe this is causing a problem because they are interpreted as strings instead of integers. Removing the quotes around the numbers appears to be the fix. I verified that if the code is changed to

$grid = GenerateGrid -Difficulty Empty
$grid.Item(0) = ('-',3,9,'-','-',4,'-','-','-')
$grid.Item(1) = (1,'-','-','-','-','-',5,'-','-')
$grid.Item(2) = ('-','-','-',2,7,'-','-','-','-')
$grid.Item(3) = (8,'-',4,'-','-','-','-','-',1)
$grid.Item(4) = ('-','-',5,'-','-','-','-',9,8)
$grid.Item(5) = (9,'-','-','-',6,2,7,4,5)
$grid.Item(6) = ('-','-',2,6,'-',9,8,5,'-')
$grid.Item(7) = (6,'-','-','-','-','-','-','-','-')
$grid.Item(8) = ('-',9,'-','-',2,'-','-',1,3)
PrintGrid -SudokuGrid $Grid
+++++++++++++++++++++++++
| - 3 9 | - - 4 | - - - |
| 1 - - | - - - | 5 - - |
| - - - | 2 7 - | - - - |
|-------+-------+------ |
| 8 - 4 | - - - | - - 1 |
| - - 5 | - - - | - 9 8 |
| 9 - - | - 6 2 | 7 4 5 |
|-------+-------+------ |
| - - 2 | 6 - 9 | 8 5 - |
| 6 - - | - - - | - - - |
| - 9 - | - 2 - | - 1 3 |
+++++++++++++++++++++++++

The same grid is output as shown above, then when running

SolveSudoku -SudokuGrid $Grid
PrintGrid -SudokuGrid $Grid
+++++++++++++++++++++++++
| 2 3 9 | 5 8 4 | 1 7 6 |
| 1 4 7 | 3 9 6 | 5 8 2 |
| 5 8 6 | 2 7 1 | 4 3 9 |
|-------+-------+------ |
| 8 2 4 | 9 5 7 | 3 6 1 |
| 7 6 5 | 1 4 3 | 2 9 8 |
| 9 1 3 | 8 6 2 | 7 4 5 |
|-------+-------+------ |
| 3 7 2 | 6 1 9 | 8 5 4 |
| 6 5 1 | 4 3 8 | 9 2 7 |
| 4 9 8 | 7 2 5 | 6 1 3 |
+++++++++++++++++++++++++

The correct output is then displayed. In my module I have only used numbers and have not tested for when numbers are initialized with ' '.

However, your issue brings up a good point. There isn't a very intuitive way for someone to initialize a custom puzzle. I will make a branch to add a function to allow a user to easily generate and solve a custom puzzle.

This product started as a school project so I can't guarantee I'll get it done quickly, but that would be a cool feature to implement. If you would like to help with it, feel free to fork a copy and submit a PR.

Let me know if anything is unclear or if you have any questions.

[LiquidDeath911]

I’m still pretty new to GitHub, so not sure the best place to ask this. Have you thought about doing any kind of GUI? I know PS is not the best language for creating GUIs.

[DavisHenckel]

I’m still pretty new to GitHub, so not sure the best place to ask this. Have you thought about doing any kind of GUI? I know PS is not the best language for creating GUIs.

I did think of building a GUI for this but I don't really see the value considering PowerShell is so much slower at solving Sudoku puzzles compared to other languages. I think if a GUI were to be built, C# and WPF could be useful, but then at that point, it seems like you may as well write the whole solver in C# instead of PowerShell.

[DavisHenckel]

Solved on PR #20