Divisors enumerator

divisors.rs

pub fn divisors(with: u64) -> Vec<u64> {
    assert_ne!(with, 0, "cannot find divisors with 0");
    let at_most = ((with as f64).sqrt() * 2.0).floor() as usize;
    let mut divs = Vec::with_capacity(at_most);
    for i in (1..)
        .filter(|&i| with % i == 0)
        .take_while(|&i| i * i <= with)
    {
        divs.push(i);
        if i * i != with {
            divs.push(with / i);
        }
    }
    divs.sort_unstable();
    divs
}