Generating unique IDs for unique sudokus

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Generating unique IDs for unique sudokus

Postby ThemePark » Fri Oct 03, 2008 4:26 am

Again more of a programming related question, but still.

I've been wondering if there's a way of creating a unique ID for a sudoku based on the solved state, that gives the same ID for two sudokus if one of them can somehow be changed into the other through rotation, flipping, row/column switching and so on.

I've been unable to come up with a way myself, so is it really necessary to actually make the possible changes to a sudoku to see if it's equal to another sudoku?
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re: Generating unique IDs for unique sudokus

Postby Pat » Sun Oct 05, 2008 7:38 am

ThemePark wrote:I've been wondering if there's a way of creating a unique ID for a sudoku based on the solved state, that gives the same ID for two sudokus if one of them can somehow be changed into the other through rotation, flipping, row/column switching and so on.

I've been unable to come up with a way myself, so is it really necessary to actually make the possible changes to a sudoku to see if it's equal to another sudoku?


the "unique ID for a sudoku" is obtained by canonicalization.
    there are various ways to canonicalize -- choose one way and stick to it.
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