Programming Challenge - Rust - Roman Numerals Checkpoint 3

main.rs

fn make_roman_numeral(my_int: i32) -> String {
    let descending = get_roman_numerals_descending();
    let mut roman_numeral = String::new();
    let mut remainder = my_int;

    // find the largest roman numeral smaller than remainder,
    // append the roman character, and deduct from the remainder,
    // if roman numeral is not smaller, try the next valid subtractor.
    // e.g. if remainder is smaller than 10, X, then check if remainder
    // is smaller than 9, IX, else go down to next numeral, V.
    while remainder > 0 {
        if remainder == 0 {
            break;
        }

        for (i, rn) in descending.iter().enumerate() {
            if rn.value <= remainder {
                roman_numeral.push_str(&rn.txt);
                remainder -= rn.value;
                break;
            }

            let next_valid_subtractor = subtractor_value(&descending, i);
            if next_valid_subtractor.is_some() {
                let next_sub = next_valid_subtractor.unwrap();
                if next_sub.value <= remainder {
                    roman_numeral.push_str(&next_sub.txt);
                    remainder -= next_sub.value;
                    break;
                }
            }
        }
    }

    roman_numeral
}