Sudoku: Difference between revisions

=={{header|Ruby}}==

Example of a back-tracking solver, from [[wp:Algorithmics of sudoku]]

<lang ruby>def read_matrix(fh)

matrix = []

def solve_sudoku(matrix)

options = []

(0..8).each { |i|

p = permissible(matrix, i, j)

# If nothing is permissible, there is no solution at this level.

options.push({:i => i, :j => j, :permissible => p})

}

return matrix if options.length == 0

# If there is an option with only one solution, set it and re-check permissibility

mtmp[omin[:i]][omin[:j]] = v

ret = solve_sudoku(mtmp)

}

# We did an exhaustive search on this branch and nothing worked out.

end

end

def print_matrix(matrix)

return

end