Help optimize D solution to phone encoding problem: extremely slow performace.

[Sergey]

On Sunday, 14 January 2024 at 17:11:27 UTC, Renato wrote:
> If anyone can find any flaw in my methodology or optmise my 
> code so that it can still get a couple of times faster, 
> approaching Rust's performance, I would greatly appreciate 
> that! But for now, my understanding is that the most promising 
> way to get there would be to write D in `betterC` style?!

I've added port from Rust in the PR comment. Can you please check 
this solution?
Most probably it need to be optimized with profiler. Just 
interesting how close-enough port will work.