Can someone explain what is going on here

Some A-hole always has a one line solution that makes me feel ashamed for all the spaghetti code I wrote! ;)

Really should be added that if a character isnt in the given alphabet it should be ignored. I wasted an hour trying to figure out what was going wrong. Would have been an OK kata otherwise, as is it left a bad taste in my mouth.

I don't get it at all, can someone give me a hint as to what I'm supposed to do to even start this

That took me several days, and my code is awful, but that was super satisfying to finally solve!

I like this solution best. I feel dumb for wasting time with a prime sieve, when obviously its not needed, ugh!

In general terms an integral is assumed to be the definite integral, this exercise is looking for the indefinate integral.

This isn't an integral, it's an anti derivative

-1 and 1 are equivalent modulo 2

My thoughts as well. The descriptiuon of this is pretty poor.

This isnt cheating imo, he went out and found a bignum. Then used it in the code he wrote. Are we supposed to rewrite every library function we use?

Definitely way better than the highest voted one, and its not even close!

I guess it might not be as readable, but I really like the elegance of this over the standard ternary!