const PREFIX: &str = "Pl";
const FACTORS_VOWELS: [(u32, char); 3] = [(3, 'i'), (5, 'a'), (7, 'o')];
const SUFFIX: &str = "ng";
const MAX_STRING_LENGTH: usize = (PREFIX.len() + 1 + SUFFIX.len()) * FACTORS_VOWELS.len();

pub fn raindrops(n: u32) -> String {
	let mut out = String::with_capacity(MAX_STRING_LENGTH);

	FACTORS_VOWELS.iter().for_each(|&(factor, vowel)| {
		if (n % factor).eq(&0) {
			out.push_str(PREFIX);
			out.push(vowel);
			out.push_str(SUFFIX);
		}
	});

	if out.is_empty() {
		n.to_string()
	} else {
		out
	}
}