Not a kata issue!

Take the 2nd row and 2nd col number for example (1)

2nd row sum --> 8

2nd col sum --> 6

So, the answer is 8 + 6 - 1 --> 13

I was being Pythonic when I wrote this. I would agree that x!=0 is more readable. https://docs.python-guide.org/writing/style/

It could equally have been used and would have been more readable IMO. As to why it was not? Perhaps the author preferred a shorter solution, or perhaps they find it just as readable, perhaps perhaps perhaps...

It is part of the loop, and it filters all x that are not a falsy value (0, False, empty string, etc). Look up list comprehension for more details.

can someone tell me what is the role played here by "if x" after for loop in the program

Much better than the top one. Cleanest and most intuitive so far.

Still linear though.

It's that I wanted to do (but something went wrong)

super dig this one

it's not better in terms of time complexity as it would have O(2n) time complexity compare to the first one which has O(n)
and that's because this solution iterates through the list twice:
1- on the construction of the first liste comprehension
2- when counting the number of zeros in the list

Thank you!

I love this solution, definitely better than what's #1. Very simple and intuitive

I understand now, the '0's are considered False so they are skipped. Thank you