projecteuler.net/026/main.rs

use std::collections::HashSet;

fn pr(s: &Vec<u8>) {
    for c in s.iter() { print!("{}", c); }
    println!("");
}

fn dv(k: u32) -> Vec<u8> {
    let mut rms = HashSet::new();
    let mut res: Vec<u8> = Vec::new();
    let mut n = 1u32;
    loop {
        if rms.contains(&n) {
            break;
        }
        rms.insert(n);
        if n == 0 { res.clear(); res.push(0); break; }
        while n < k { n *= 10; res.push(0u8); }
        let m = n / k;
        if m > 10 {
            println!("fail! {}", m);
        }
        res.pop();
        //print!("{}", m);
        res.push(m as u8);
        n = n - m * k;
    }
    return res;
}

fn main() {
    let mut max = 0;
    let mut max_d = 0;
    for i in 1..1000 {
        let r = dv(i);
        if r.len() > max {
            max_d = i;
            max = r.len();
        }
        //pr(&r);
    }
    println!("{}", max_d);
}