curriculum/challenges/english/blocks/learn-classes-and-objects-by-building-a-sudoku-solver/6606cd69f56e27516583b0cc.md
Now you need to calculate the starting row index for the 3x3 square within the board grid and ensure that the starting row index for each 3x3 square is a multiple of 3.
This can be achieved by taking the result of the integer division row // 3 multiplied by 3. Replace pass with a variable row_start and assign it (row // 3) * 3.
You should delete pass and declare a variable row_start with the value of (row // 3) * 3.
({ test: () => assert(runPython(`_Node(_code).find_class("Board").find_function("valid_in_square").find_body().is_equivalent("row_start = (row//3)*3")`)) })
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))
--fcc-editable-region--
def valid_in_square(self, row, col, num):
pass
--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)