curriculum/challenges/english/blocks/learn-classes-and-objects-by-building-a-sudoku-solver/6606db6a23a1455a402f91ae.md
Within the is_valid method, check if the number is valid for insertion in the specified row by calling the valid_in_row() method with row and num as arguments, and assign the result to a variable valid_in_row. Remember to use self to reference the methods of the current instance.
You should declare a variable valid_in_row and assign it self.valid_in_row(row, num).
({ test: () => assert(runPython(`_Node(_code).find_class("Board").find_function("is_valid").find_variable("valid_in_row").is_equivalent("valid_in_row = self.valid_in_row(row, num)")`)) })
class Board:
def __init__(self, board):
self.board = board
def find_empty_cell(self):
for row, contents in enumerate(self.board):
try:
col = contents.index(0)
return row, col
except ValueError:
pass
return None
def valid_in_row(self, row, num):
return num not in self.board[row]
def valid_in_col(self, col, num):
return all(self.board[row][col] != num for row in range(9))
def valid_in_square(self, row, col, num):
row_start = (row // 3) * 3
col_start = (col // 3) * 3
for row_no in range(row_start, row_start + 3):
for col_no in range(col_start, col_start + 3):
if self.board[row_no][col_no] == num:
return False
return True
--fcc-editable-region--
def is_valid(self, empty, num):
row, col = empty
--fcc-editable-region--
puzzle = [
[0, 0, 2, 0, 0, 8, 0, 0, 0],
[0, 0, 0, 0, 0, 3, 7, 6, 2],
[4, 3, 0, 0, 0, 0, 8, 0, 0],
[0, 5, 0, 0, 3, 0, 0, 9, 0],
[0, 4, 0, 0, 0, 0, 0, 2, 6],
[0, 0, 0, 4, 6, 7, 0, 0, 0],
[0, 8, 6, 7, 0, 4, 0, 0, 0],
[0, 0, 0, 5, 1, 9, 0, 0, 8],
[1, 7, 0, 0, 0, 6, 0, 0, 5]
]
gameboard = Board(puzzle)