Sudoku Solver v1

easy.py

from collections import defaultdict

class Sudoku:
    def __init__(s, board):
        s.board = board
    def __repr__(s):
        return "\n".join(" ".join(map(str, xs)) for xs in s.board)
    def gen_dict(s):
        sq = lambda xs, i: xs[3 * (i//3) : 3 * (1 + i//3)]
        s.opts = defaultdict(lambda: {*range(1, 10)})
        # Rows & Columns & Squares
        for x in range(9):
            column = {row[x] for row in s.board}
            for y in range(9):
                if not s.board[y][x]:
                    s.opts[y, x] -= column
                    s.opts[y, x] -= {*s.board[y]}
                    s.opts[y, x] -= {n for row in
                        sq(s.board, y) for n in sq(row, x)}
        return s.opts
    def apply_singles(s):
        flip = False
        for (y, x), opts in s.opts.items():
            if len(opts) == 1:
                s.board[y][x] = opts.pop()
                flip = True
        return flip
    def reduce_1(s):
        flip = True
        while flip:
            s.gen_dict()
            flip = s.apply_singles()

idk_what_this_was.py

from collections import defaultdict

nby = lambda y, x: (y // 3, x // 3)
class Sudoku:
    def __init__(s, board):
        s.board = board
    def __repr__(s):
        return "\n".join(" ".join(map(str, xs)) for xs in s.board)
    def gen_dict(s):
        sq = lambda xs, i: xs[3 * (i//3) : 3 * (1 + i//3)]
        s.opts = defaultdict(lambda: {*range(1, 10)})
        # Rows & Columns & Squares
        for x in range(9):
            column = {row[x] for row in s.board}
            for y in range(9):
                if not s.board[y][x]:
                    s.opts[y, x] -= column
                    s.opts[y, x] -= {*s.board[y]}
                    s.opts[y, x] -= {n for row in
                        sq(s.board, y) for n in sq(row, x)}
        return s.opts
    def apply_singles(s):
        flip = False
        for (y, x), opts in s.opts.items():
            if len(opts) == 1:
                s.board[y][x] = opts.pop()
                flip = True
        return flip
    def reduce_1(s):
        flip = True
        while flip:
            s.gen_dict()
            flip = s.apply_singles()
            if not flip:
                s.group_dicts()
                flip = s.reduce_2()
    def group_dicts(s):
        s.rows = defaultdict(list)
        s.cols = defaultdict(list)
        s.blocks = defaultdict(list)
        for (y, x), opts in s.opts.items():
            s.blocks[nby(y, x)] += opts
            s.rows[y] += opts
            s.cols[x] += opts
    def reduce_2(s):
        flip = False
        for (y, x), opts in s.opts.items():
            for value in opts:
                if (s.blocks[nby(y,x)].count(value) == 1 or
                    s.rows[y].count(value) == 1 or
                s.cols[x].count(value) == 1):
                    s.board[y][x] = value
                    flip = True
        return flip

puzzle = [[0,9,4,0,0,0,0,8,5],
          [5,0,7,0,0,1,0,0,0],
          [0,0,0,0,0,0,0,0,0],

          [0,0,0,9,4,0,0,0,6],
          [0,7,0,0,2,5,0,4,0],
          [0,0,9,0,6,0,0,0,8],

          [0,5,0,0,0,3,8,9,0],
          [0,0,0,0,0,0,0,6,3],
          [0,2,0,0,9,0,7,0,0]]

a = Sudoku(puzzle)
a.reduce_1()
a