sudoku_checker.py

import sys
from math import sqrt

errors = 0


def is_uniq(lst):
    return len(list(set(lst))) is len(lst)


def flatten(lst):
    res = []
    for item in lst:
        if isinstance(item, list):
            res.extend(flatten(item))
        else:
            res.append(item)
    return res


raw_sudoku = []

if len(sys.argv) <= 1:
    print("Not enough arguments")
    exit(1)

filename = sys.argv[1]

with open(filename) as f:
    for line in f:
        raw_sudoku.append([int(x) for x in line.split(" ")])

# Check dimensions
height = len(raw_sudoku)
width = len(raw_sudoku[0])

if width is not height:
    print("Width and height not the same")
    errors += 1

for i in range(0, height):
    row = raw_sudoku[i]
    if len(row) is not width:
        print("Row " + str(i+1) + " is not long enough")
        errors += 1


# Check rows
for i in range(0, len(raw_sudoku[0])):
    row = raw_sudoku[i]
    if not is_uniq(row):
        print("Doubles on line " + str(i+1))
        errors += 1

# Check columns
for i in range(0, len(raw_sudoku)):
    items = [row[i] for row in raw_sudoku]
    if not is_uniq(items):
        print("Doubles on columns " + str(i+1))
        errors += 1

# Create sections
sec_width = int(sqrt(len(raw_sudoku)))
sections = []

for y in range(0, sec_width):
    for x in range(0, sec_width):
        # ~ Magic ~
        section = [
            row[x*sec_width:(x+1) * sec_width]
            for row in raw_sudoku[y*sec_width:(y+1) * sec_width]
        ]

        sections.append(section)

# Check sections
for i in range(0, sec_width):
    section = sections[i]
    if not is_uniq(flatten(section)):
        print("Section " + str(i + 1) + " is not unique")
        errors += 1


if errors is 0:
    print("No errors :)")