Actually it's what happens when a software engineer does his everyday job.

вот что происходит когда физмат попадает в IT

Can anyone explain the math for my dumb brain, because I DO NOT understand how 3 (1+2+3+...) and 5 (1+2+3+...) becomes whatever that return is.

This is the only solution I saw with O(1) complexity, but I'm still processing the maths behind it, haha.

Hey, integer division is fundamental to number theory; and it's harder to get more "pure math" than that! :)

i think this solution is best practice

3: int
3d: double

The posts here are visible in the homepage for everyone too if not marked as spoilers. That's why when disclosing information about the solution, they should be marked. There are comments that don't need it, see the ones below, most of them don't.

Chrono79, what are you doing in the comments of a solution, if not spoiling the solution? 🤔

Indeed this is way smarter and it's really elegant. So easy to read and understand.

Please, use spoiler flag next time.

It's great. Almost pure math =) "Almost" because of "integer division" =)

It's great. Almost pure math =)