collatz.rs

// Collatz Conjecture

fn even_or_odd(num: &u32) -> u32 { num % 2 }
fn even(num: u32) -> u32 { num / 2 }
fn odd(num: u32) -> u32 { 3 * num + 1 }

fn collatz(mut num: u32) {
    while num != 1 {
        // println!("Processing: {}", num);
        let n_type = even_or_odd(&num);
        match n_type {
            0 => num = even(num),
            1 => num = odd(num),
            _ => println!("Failed: {}", n_type),
        }
    }
    // println!("End: {}", num);
    assert_eq!(num, 1u32);
}

fn main () {
    let start: u32 = 1;
    let end: u32 = 100;
    for i in start..end + 1 {
        // println!("Start: {}", &i);
        collatz(i as u32);
    }
}