sudoku-solver.py

import sys

board = []


def solve():
    find = find_empty_cell()
    if not find:
        return True
    else:
        row, col = find

    for i in range(1,10):
        if is_valid(i, (row, col)):
            board[row][col] = i

            if(solve()):
                return True
            board[row][col] = 0

def is_valid(num, pos):
    #row
    for i in range(len(board[0])):
        if board[pos[0]][i] == num and pos[1] != i:
            return False

    for i in range(len(board)):
        if board[i][pos[1]] == num and pos[0] != i:
            return False      
 
    box_x = pos[1] // 3
    box_y = pos[0] // 3

    for i in range(box_y * 3, box_y * 3 + 3):
        for j in range(box_x * 3, box_x * 3 + 3):
            if board[i][j] == num and (i, j) != pos:
                return False

    return True

def print_board():
    for i in range(len(board)):
        if i % 3 == 0 and i != 0:
            print("- - - - - - - - - - - -")

        for j in range(len(board[0])):
            if j % 3 == 0 and j != 0:
                print(" | ", end="")

            if j == 8:
                print(board[i][j])
            else:
                print(str(board[i][j]) + " ", end="")



def find_empty_cell():
    for i in range(len(board)):
        for j in range(len(board[0])):
            if board[i][j] == 0:
                return (i, j)
    return None
                
sudoko_text = ""

try:
    with open (sys.argv[1]) as file:
        for i, line in enumerate(file):
            sudoko_text += str.rstrip(line)
except:
    print("- - - - - - - - - - - - - - - - -")
    print("File of " + sys.argv[1] + " could not be found.")
    print("- - - - - - - - - - - - - - - - -")

for num in sudoko_text:
    board.append(int(num))

#split chunks
def chunks(n):
    for i in range(0, len(board), n):
        yield board[i:i + n]

board = list(chunks(9))

solve()
print_board()