Nothing node.js specific, but an awful lot of js specific

Divide et impera

I have a JS algorithm that gets the correct solution, plenty fast enough to not timeout.
However I am very stuck with overflow errors. If I use BigInts on a local version of Node it gets the correct answer instantly.
The kata is on an old version of Node without BigInts.
I have tried to many things. Spamming the modulus, got rid of any bitwise, tweeked my alg to keep numbers slightly lower - no luck. The best I've managed is around half of the final batch of 500 tests correct, the other half overflowed so turned out wrong. I'm at a loss.

Any tips? Efficiency not a concern since I have bags of time spare

Reading the solutions for this when compared to my, uhh, naive method was a trip. Nice kata, thoroughly enjoyed

Ohh I didn't know to check the node version... silly me.
Thanks for the heads up - I will do a manual implementation

It is not banned, but note the language version used. This kata currently only supports Node 8, and Array.flat wasn't added to node until version 11.

I only use it once per puzzle so I could just manually impliment it, but it seems odd for sure

Am I crazy, is Array.flat() banned? If so, why? Code including .flat() that executes in node or in console won't on here

I think that there's more solution based on another paper (or at least mine and monadius' is, which makes it two :) ). I am not sure why, is it more googleable, or what. I think I've seen the one you used but I found the other one easier to implement.

I thought my solution was super janky but once I got it working it was under 2.0s.

Did I just stumble upon a cracked algorithm in my research?

Reading through other solutions and there's fancy stuff going on I don't begin to understand... to MDN I go :)

description updated

I was thinking the same thing. An example would help quite a bit.