projecteuler.net/010/main.rs

// based on ../007/main.rs

const SIZE: usize  = 2000000; // 10 as test should be =17
type Rs = [bool; SIZE + 1];

fn remove_divs(m: usize, xs: &mut Rs) {
    let mut i = m + m;
    while i <= SIZE {
        xs[i] = false;
        i += m;
    }
}

fn get_next_p(m_from: usize, xs: &Rs) -> Option<usize> {
    for k in (m_from + 1)..=SIZE {
       if xs[k] { return Some(k); } 
    }
    return None;
}

fn main() {
    let mut xs: Rs = [true; SIZE + 1];
    let mut sum = 0usize;
    let mut last_p = 1;
    loop {
        match get_next_p(last_p, &xs) {
            Some(p) => {
                sum += p;
                last_p = p;
            },
            None => break
        }
        remove_divs(last_p, &mut xs);
    }
    println!("sum: {}", sum);
}