Advent of Code 2020 - Day 4: Passport Processing

passport_processing.rs

fn main() {
    let part1 = count_valid_passports(INPUT, part1_filter);
    let part2 = count_valid_passports(INPUT, part2_filter);

    println!("Part 1: {}", part1);
    println!("Part 2: {}", part2);
}

fn count_valid_passports(batch: &str, filter: fn(&str, &str) -> bool) -> usize {
    batch
        .split("\n\n")
        .filter(|p| {
            p.split_whitespace()
                .map(|kv| kv.split_once(':').unwrap())
                .filter(|&(k, v)| k != "cid" && filter(k, v))
                .count()
                == 7
        })
        .count()
}

fn part1_filter(_: &str, _: &str) -> bool {
    true
}

fn part2_filter(key: &str, value: &str) -> bool {
    match key {
        "byr" => (1920..=2002).contains(&value.parse().unwrap()),
        "iyr" => (2010..=2020).contains(&value.parse().unwrap()),
        "eyr" => (2020..=2030).contains(&value.parse().unwrap()),
        "hgt" => match &value[value.len() - 2..] {
            "cm" if (150..=193).contains(&value[..value.len() - 2].parse().unwrap()) => true,
            "in" if (59..=76).contains(&value[..value.len() - 2].parse().unwrap()) => true,
            _ => false,
        },
        "hcl" => {
            value.len() == 7
                && value.as_bytes()[0] == b'#'
                && usize::from_str_radix(&value[1..], 16).is_ok()
        }
        "ecl" => ["amb", "blu", "brn", "gry", "grn", "hzl", "oth"].contains(&value),
        "pid" => value.len() == 9 && value.parse::<usize>().is_ok(),
        _ => panic!("Unrecognised field"),
    }
}