Python code for sudoku solver [Backtracking Problem]

Sudoku Solver.py

def isSafe(i, j, num, n):
    for k in range(n):
        if board[i][k] == num or board[k][j] == num:
            return False

    sx, sy = (i // 3) * 3, (j // 3) * 3

    for x in range(sx, sx + 3):
        for y in range(sy, sy + 3):
            if board[x][y] == num:
                return False

    return True


def sudokuSolver(i, j, n):
    if i == n:
        for r in range(n):
            for c in range(n):
                print(board[r][c], end=" ")
            print()
        return

    if j == n:
        return sudokuSolver(i + 1, 0, n)

    if board[i][j] != 0:
        return sudokuSolver(i, j + 1, n)

    for num in range(1, n + 1):
        if isSafe(i, j, num, n):
            board[i][j] = num

            if sudokuSolver(i, j + 1, n):
                return True

        board[i][j] = 0

    return False


board = [[5, 3, 0, 0, 7, 0, 0, 0, 0],
         [6, 0, 0, 1, 9, 5, 0, 0, 0],
         [0, 9, 8, 0, 0, 0, 0, 6, 0],
         [8, 0, 0, 0, 6, 0, 0, 0, 3],
         [4, 0, 0, 8, 0, 3, 0, 0, 1],
         [7, 0, 0, 0, 2, 0, 0, 0, 6],
         [0, 6, 0, 0, 0, 0, 2, 8, 0],
         [0, 0, 0, 4, 1, 9, 0, 0, 5],
         [0, 0, 0, 0, 8, 0, 0, 7, 9]]

sudokuSolver(0, 0, len(board))