v.rs

use std::time::Instant;

// From jakobrs/primes, using the kimwalisch/primesieve library
use primesieve::PrimesieveIterator;

fn main() {
    for n in 5..=20 {
        let count = ((5. / 4. * n as f64).exp() / n as f64) as u64;

        let before = Instant::now();

        let (v, i) = PrimesieveIterator::new_start_stop(1, count)
            .enumerate()
            .skip(1)
            .take(count as usize)
            .map(|(i, p)| {
                let i = i as i64;
                let p = p as i64;
                let res = n * i + 1 - p;

                (res, i)
            })
            .max()
            .unwrap();

        println!(
            "V_{n} = {v} (at i = {i}) in {elapsed:?}",
            elapsed = before.elapsed()
        );
    }
}