Learn Classes and Objects by Building a Sudoku Solver - Step 60

Python
1

Tell us what’s happening:

Sorry to bother you…
My main problem here is that I do know which one is the “innermost if statement”. My English is not very good but I believe is the 3rd one. Also, I read this post: How to Use Conditional Statements in Python – Examples of if, else, and elif which is very good but did not help me so much.
My second issue is to “set the current cell” which I believe is the self.solver. Am I doing all wrong? :slight_smile:

Your code so far

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

    def is_valid(self, empty, num):
        row, col = empty
        valid_in_row = self.valid_in_row(row, num)
        valid_in_col = self.valid_in_col(col, num)
        valid_in_square = self.valid_in_square(row, col, num)
        return all([valid_in_row, valid_in_col, valid_in_square])

# User Editable Region

    def solver(self):
        if (next_empty := self.find_empty_cell()) is None:
            return True
        for guess in range(1, 10):
            if self.is_valid(next_empty, guess):
                row, col = next_empty
                self.board[row][col] = guess
                if self.solver() == 0:
                    return True

# User 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)

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Challenge Information:

Learn Classes and Objects by Building a Sudoku Solver - Step 60

2

Actually it says: aftet the innermost if statement, …therefore, I need to add this line: self.board[row][col] = 0

3

waooooo I made it …I was right about the above line I added…The code did not run becaue of the wrong position of the line: it should got after retur True: I am so stupido… :slight_smile: