raindrops.rs

pub fn raindrops(n: u32) -> String {
    let mut result = String::new();

    if let Some(v) = is_factor_of_three(n) {
        result.push_str(v);
    }

    if let Some(v) = is_factor_of_five(n) {
        result.push_str(v);
    }

    if let Some(v) = is_factor_of_seven(n) {
        result.push_str(v);
    }

    if result.is_empty() {
        result.push_str(&n.to_string())
    }

    return result;
}

fn is_factor_of_three<'a>(n: u32) -> Option<&'a str> {
    if n % 3 == 0 {
        return Some("Pling");
    }
    return None;
}

fn is_factor_of_five<'a>(n: u32) -> Option<&'a str> {
    if n % 5 == 0 {
        return Some("Plang");
    }
    return None;
}

fn is_factor_of_seven<'a>(n: u32) -> Option<&'a str> {
    if n % 7 == 0 {
        return Some("Plong");
    }
    return None;
}