When I was nearly done with this, I realised that identical_possibilities is the general case of one_possibility, in which i=1, and unique_possibilities is just the general case of only_instance in which i=1. In any possible update this will be top of my list to address, along with cleaning up box_line_intersection.
To solve a particular sudoku, type in the starting values (0 taking the place of no value) into a single line of a document, save with the extension .sdk . Should not end with a new line. Then run:
python sudoku.py <path/to/document.sdk>
To solve multiple sudokus one after another, simply add more rows to your document. To create a new file with the completed values, run:
python sudoku.py <path_to_document.sdk> <path/to/output.sdk>
I included sample_sudoku.sdk which contains 3 sudokus so you can test it.
The term subgrid will be used when talking generally about a row, column, or box.
All possibilities true for all squares which have no value
while sudoku not completed:
for square in grid:
for possibilities in square:
if possibility is revealed in the same row, column or box:
remove possibility from square.
return start
if only one possibility:
square value = possibility
return start
for subgrid in grid:
for possibility not determined in subgrid:
if possibility is only possible in one square in subgrid:
squares value = possibility
return start
for i in range(2,9):
for subgrid in grid:
if there exist i squares with exactly i
identical possibilities in subgrid:
remove these possibilities from all other
squares in subgrid, return start
if there exist i squares which share i unique
possibilities not found anywhere else in the subgrid:
remove all other possibilities from these
x squares, return start
for subgrid in grid:
for possibilities not yet determined in subgrid:
if this possibility is only found in squares which are
members of the same box:
remove this possibility from
all other squares in this box, return start
for box in boxes:
for possibilities not yet determined in box:
if this possibility is only found in squares which
are members of the same row or column:
remove this possibility from all other squares
in this row or column, return start
brute force a solution
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