sudoku.py

def solveSudoku(board):
    """
    :type board: List[List[str]]
    :rtype: void Do not return anything, modify board in-place instead.
    """
    while True:
        board = check_row(board=board)
        board = check_col(board=board)
        board = check_group(board=board)

        if check_set(board) == True:
            break

    return board


def check_row(board):
    sudoku = {str(i) for i in range(1, 10)}
    rows = []
    for idx, row in enumerate(board):
        rows.append([cell for cell in row if cell != '.' and not isinstance(cell, set)])

    for idx, b in enumerate(board):
        for idy, cell in enumerate(b):
            if cell == '.':
                board[idx][idy] = sudoku - set(rows[idx])
            elif isinstance(cell, set):
                data = cell - set(rows[idx])
                board[idx][idy] = data if len(data) > 1 else ''.join(data)

    return board


def check_col(board):
    cols = []
    board = [list(b) for b in zip(*board)]
    for idx, col in enumerate(board):
        cols.append([cell for cell in col if cell != '.' and not isinstance(cell, set)])

    for idx, b in enumerate(board):
        for idy, cell in enumerate(b):
            if isinstance(cell, set):
                data = cell - set(cols[idx])
                board[idx][idy] = data if len(data) > 1 else ''.join(data)

    return [list(b) for b in zip(*board)]


def check_group(board):
    # check group
    board = [list(b) for b in zip(*board)]
    
    # group
    matrix = [[] for _ in range(len(board))]
    count, group = 0, 0
    for i in range(0, 9):
        c = 0
        for j in range(0, 9, 3):
            matrix[group + c].extend(board[i][j:j + 3])
            c += 1

        count += 1
        if count % 3 == 0:
            group = count

    # check
    row = [[] for _ in range(len(board))]
    for idx, m in enumerate(matrix):
        for cell in m:
            if not isinstance(cell, set):
                row[idx].append(cell)

    for idx, m in enumerate(matrix):
        for idy, cell in enumerate(m):
            if isinstance(cell, set):
                data = cell - set(row[idx])
                matrix[idx][idy] = data if len(data) > 1 else ''.join(data)

    # group
    board = [[] for _ in range(len(board))]
    count, group = 0, 0
    for i in range(0, 9):
        c = 0
        for j in range(0, 9, 3):
            board[group + c].extend(matrix[i][j:j + 3])
            c += 1

        count += 1
        if count % 3 == 0:
            group = count

    return [list(b) for b in zip(*board)]


def check_set(board):
    for b in board:
        for cell in b:
            if isinstance(cell, set):
                return False
    return True