bro thats not O(n) thats O(k * T + N log N)

Thank you, I actually agree with both your changes. Self-describing code is always a good idea (especially when there are no comments) and using next(iter(...)) or set.pop() is definitely better than creating an entire tuple just to access one item.

yeah, doesn't seem like it handles leading 0s in the cases 00, 01, 02, 03, 04, 05, 06, 07, 08, or 09

none of which appear in the test cases :)

regex is everything!

I really need to learn!

Yeah but it's not very efficient as it uses for loops. See my solution. BTW I had initially came up with this solution but I improved before submitting.

i like this one, clean with easy methods

really nice. unkilled me

I really need to learn regex. Wow. Well done!

yor're expert regex

What does (?!$)|$)){4}(?=$) accomplish?

For me, every single one liner is very readable, but long blocks of code are unreadable.

Agree with you. 99% of one-line-solutions are badly readable and looks like a mess. Really cannot understand a beauty of those solutions. Moreover, I guess, most of guys think, that more short code is, more fast it is :)