The New Sudoku Players' Forum

[urhegyi]

I created this today. The shape I invented myself. Can anyone explain how you can test if the grid is valid before starting to generate? The result was it found a solution, so I had luck. Is there more information available on this topic?

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..8.....77.9...2..........55...8......4.....623.....6.....2.....1.........7...... 222777888212718818232777778233333668213516618443566669443565999414515919444555999 ED=3.4/1.7/1.7

I will adjust the list when new examples are found:
JS:

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.72.....9...2...9.......48....16........7.......6.....6.....3....3............1.. 222777888212718818232777778233333668213516618443566669443565999414515919444555999 ED=2.9/1.2/1.2
..84..6............2......5.....9...3.5........1....4.4...........1..579......... 222777888212718818232777778233333668213516618443566669443565999414515919444555999 ED=3.0/1.5/1.5
..8.....77.9...2..........55...8......4.....623.....6.....2.....1.........7...... 222777888212718818232777778233333668213516618443566669443565999414515919444555999 ED=3.4/1.7/1.7

JSX:

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28.7.......76...3.......483.........1.......2.2...6..5..................53...4... 222777888212718818232777778233333668213516618443566669443565999414515919444555999 ED=2.8/1.2/1.2

JSB:

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......7.6....3...........................8.......9.....4.6........7..6...12...... 222777888212718818232777778233333668213516618443566669443565999414515919444555999 ED=2.8/1.2/1.2

JSBX:

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...5.......1..........6..3..1.2..9...2.....8.........1.....5......3.....1.7...... 222777888212718818232777778233333668213516618443566669443565999414515919444555999 ED=3.4/1.2/1.2

[Hajime]

I created this today. The shape I invented myself. Can anyone explain how you can test it on validity?

I think when you solve it with normal methods, that leads to a solution, it is valid.
If you solve it with T&E (brute force/backtrack) that leads to 1 solution it is valid too. If a second solution is possible, it is invalid.
If you can not solve it because it leads to empty cell with no candidates left, it is invalid too.

[urhegyi]

I created this today. The shape I invented myself. Can anyone explain how you can test it on validity?

I think when you solve it with normal methods, that leads to a solution, it is valid.
If you solve it with T&E (brute force/backtrack) that leads to 1 solution it is valid too. If a second solution is possible, it is invalid.
If you can not solve it because it leads to empty cell with no candidates left, it is invalid too.

Because it's a shape I created myself I wasn't sure it would lead to a solution. Can this be checked before starting to generate?

[Hajime]

Can this be checked before starting to generate?

I or SiSeSuSo can not. First I need a solution, so puzzle fully solved. Then the Generate action can start.
To solve it I fill the first row with 123456789 and then brute force/backtrack until the first solution -or- no solution possible...