prime-challenge
This is a program built in response to a programming challenge we selected at work. The goal was to take in a number, 0 >= 10,000,000 and output 4 primes that add up to that number, otherwise output "Impossible!". You are allowed to repeat primes.
Why Rust
One of my immediately desires with this project was to take it to logical extreme of optimization. This is why I decided to use Rust for it. The language choice was completely open and I knew I'd likely want parallel solution to get the fastest time that I could.
In addition to making parallel solutions easier to write, Rust is one of my favorite languages to use. Finally, it has the nice feature of trying to compete with C++ so it is no slouch when it comes to speed.
Library Choice
Many challenges, folks opt to not use any libraries or limit their usage to things outside of the core problem. I didn't take that path myself as I'm still learning Rust and part of learning a language is working with other people's code and libraries.
I decided from the start that I didn't want to implement a sieve of Eratosthenes. I've implemented them in the past and while they were interesting the first few times, I opted to use a library to cover this for me. A quick check of libraries available for primes led me to a pretty immediate answer: Primal. This gives me the two things I'd be implementing myself, caching and optimization.
Late in the project I wanted to add parallelism to my solution. In the past I've
just use the built in
spawn and just build up
any additional logic myself. Recently though,
Jim Blandy gave a talk at
PDX Rust about using Rust, from the basics to
multiple threaded solutions with different libraries used for the threadpool.
One that he mentioned looked pretty simple so I opted for it:
scoped_threadpool. It worked
wonderfully and only took me 25-30 minutes to turn my solution from a single
threaded solution to a multithreaded solution using a pool and chunking out the
work.