projecteuler.net/030/main.rs

struct Num {
    n: u32,
    digits: Vec<u8>
}

impl Num {
    fn new(n: u32) -> Num {
        let mut dsr = Vec::new();
        let mut k = n;
        while k != 0 {
            let a = (k % 10) as u8;
            k /= 10;
            dsr.push(a);
        }
        dsr.reverse();
        return Num { n, digits: dsr };
    }
    fn check(&self) -> bool {
        let mut sum = 0u32;
        for k in &self.digits {
            let d = *k as u32;
            sum += d * d * d * d * d;
        }
        return sum == self.n;
    }
}

fn main() {
    //let n = Num::new(9474);
    //for d in &n.digits { print!("{}", d) }
    //println!("");
    //println!("{}", n.check());
    let mut sum = 0u32;
    for i in 2..5_000_000u32 {
        let n = Num::new(i);
        if n.check() {
            println!("{}", n.n);
            sum += n.n;
        }
    }
    println!("{}", sum);
}