I know this is old, but for anyone reading now, sum can also accept a range (in fact, any iterable) object, which can save you some memory

Wow someone actually corrected the code instead of just hammering the one liner in

Good explanation! Thank you

By using line[:] you're making a copy of the list. If you instead just use line, you're adding the same line to the board multiple times. In that case, when you change one element to O, it changes that element in every row of the board.

You can see more here: https://docs.python.org/3/faq/programming.html#how-do-i-copy-an-object-in-python

Why do I nedd to put "line[:]" instead of just "line" when i'm declarating board? With line it turn all the items into O's

Also, floor division (integer division) is faster than true division

yeah, you're right. Thanks :)

Because of imprecisions, you could get 54.9999999999 which is not equal to 55.

This was a python 2 solution, where / is floor division; in python 3 // is the floor division operator.

when im doing that i get wrong answers on randomly chosen tests, each time different tests. For some reason i have to use // instead of /, then it always works

Finally found the problem. Hint: look how your algorithm behaves with a problematic input outside of codewars environment...

Is there any problem with this Kata in Python? In a random test case, I have the following array: [26, 9, -10, 6, 13, 22, 20, -22, -27, -13, -18, 4, -13, -4, 18, -11, 19, -26, -23, -30, 15, -13, -19, 7, -25, -2, 0, 27, 23, -11, 1, 9, -19, -20, -21, -7, -28, 7, -11, -24, 0, 22, 2, 21, 28, 27, -15, -4, -6, -19] for which the expected value is 1171 and my answer is 100. Note that the sum of absolute values is 741.