use std::time::Instant;
use rayon::prelude::*;

fn flip_coins(num_heads: u32) -> bool {
    let mut heads_in_a_row = 0;

    while heads_in_a_row < num_heads {
        if rand::random_bool(0.5) {
            heads_in_a_row += 1;
        } else {
            return false;
        }
    }

    true
}

fn main() {
    let num_heads = 20;

    // Normal version
    let start_time = Instant::now();
    while !flip_coins(num_heads) {
        continue;
    }
    println!("Normal version: {:?}", start_time.elapsed());

    // Parallel version
    let start_time = Instant::now();
    (0u64..u64::MAX)
        .into_par_iter()
        .find_any(|_| flip_coins(num_heads));
    
    println!("Parallel version: {:?}", start_time.elapsed());
}