sim.rs

use rand::distributions::Uniform;
use rand::Rng;
use rayon::prelude::*;
use std::time::Instant;

fn main() {
    let dis = Uniform::from(0..=6_u8);

    for trials in (1..).map(|x| 10usize.pow(x)) {
        let start = Instant::now();

        let result = (0..trials)
            .into_par_iter()
            .map(|_| {
                let mut rng = rand::thread_rng();
                let balls = (0..20).map(|_| rng.sample(dis));
                let mut bitset: u8 = 0;

                for ball in balls {
                    bitset |= 1 << ball;
                }

                bitset.count_ones() as f64
            })
            .sum::<f64>();

        let end = Instant::now();

        println!(
            "trials: {trials} result: {:.9} time: {:?}",
            result / trials as f64,
            end - start
        );
    }
}