1.rs

/*
Problem 1 - Multiples of 3 or 5

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below 1000.
*/

use rayon::prelude::*;
use std::collections::HashSet;

fn multiples_of(multipliers: &Vec<usize>, upper_bound: usize) -> HashSet<usize> {
    let mut results: HashSet<usize> = HashSet::new();

    // Find all of the numbers between 1 and the upper bound that are multiples of one of the numbers
    // in the multipliers vec
    for i in 1..upper_bound {
        for number in multipliers {
            if i % number == 0 {
                results.insert(i);
            }
        }
    }

    return results;
}

pub fn main() {
    let multiples = multiples_of(&vec![3, 5], 1000);
    let sum: usize = multiples.par_iter().sum();

    println!("The sum of the multiples of 3 and 5 up until 1000 is {sum}");
}