indivisible-rs/src/main.rs

/*
 * Copyright (C) 2021  Ortega Froysa, Nicolás <nicolas@ortegas.org>
 * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

use std::env;
use std::collections::VecDeque;

fn main() {
    let args:Vec<String> = env::args().collect();

    // get the first `n` primes
    let n:usize = args[1].parse().unwrap();
    let mut primes:VecDeque<u64> = VecDeque::with_capacity(n);
    // first prime
    println!("{}", 2);
    primes.push_back(2);

    let mut candidate:u64 = 3;

    while primes.len() < n
    {
        let mut is_prime = true;
        let limit = (candidate as f64).sqrt() as u64;
        for i in primes.iter().take_while(|x| **x <= limit)
        {
            if candidate % *i == 0
            {
                is_prime = false;
                break;
            }
        }

        if is_prime
        {
            println!("{}", candidate);
            primes.push_back(candidate);
        }
        candidate += 2;
    }
}