coupon_collectorRS.rs

use std::collections::HashSet;
use rand::distributions::{Distribution, Uniform};

fn coupon_colector_rs(n: i32, sims: usize) -> f32 {
    let mut needed_coupons = vec![0; sims];
    let mut rng = rand::thread_rng();
    let coupon_set = Uniform::from(1..n+1);

    for trial in 0..sims {
        let mut collected_coupons = HashSet::new();
        let mut n_collected_coupons = 0;
        let mut n_different_coupons = 0;

        while n_different_coupons < n {
            let coupon = coupon_set.sample(&mut rng);
            n_collected_coupons += 1;

            if !collected_coupons.contains(&coupon) {
                collected_coupons.insert(coupon);
                n_different_coupons += 1;
            }

        }

        needed_coupons[trial] = n_collected_coupons;
    }

    mean(&needed_coupons)
}

fn mean(numbers: &[i32]) -> f32 {
    numbers.iter().sum::<i32>() as f32 / numbers.len() as f32 
}

fn main() {
    println!("{}", coupon_colector_rs(30, 10))
}