recursion?

WOW, nice one :)

Haha,true.. I guess it's a solution from 2017 or whatever. Good catch!

??? returning reference to stack variable ???

It's clever. Can I read how you find this formula? I can write program only with "for"

This is great!, I got it down to one for loop by modifying gauss' sum slighly different. But this is true algebraic problem solving! :)

Out-of-range array access in the solution (arr[100]).
Undeclared identifiers used in the tests (size_t, RAND_MAX etc).

The loop condition is off-by-one.

Don't worry! We've all been there as well. :) Try to turn that frustration into motivation. Also - never stop improving!

I love finally finishing a Kata just so I can see the guys who figured it out on 1 line! Way to go... I'm so bad :(

Very clever ! How did yo come up with it ?

Submitted C translation. :)

I have the same problem. Don't know hot to submit...