OlympiadCode/leetcode_py/37.py

# Sudoku Solver


class Solution:
    def solveSudoku(self, board: list[list[int]]) -> None:
        def isValid(board, row, col, num):
            # Check if the number is in the current row
            for x in range(9):
                if board[row][x] == num:
                    return False
                if board[x][col] == num:
                    return False

            startRow, startCol = 3 * (row // 3), 3 * (col // 3)
            for i in range(3):
                for j in range(3):
                    if board[startRow + i][startCol + j] == num:
                        return False

            return True

        def solve(board):
            for i in range(9):
                for j in range(9):
                    if broad[i][j] == ".":
                        # Try all numbers for empty cell
                        for num in map(str, range(1, 10)):
                            if isValid(board, i, j, num):
                                board[i][j] = num
                                if solve(board):
                                    return True
                                board[i][j] = "."

                        return False
            return False

        solve(board)