aoc/year2020/
day04.rs

1//! # Passport Processing
2//!
3//! [Regular expressions](https://en.wikipedia.org/wiki/Regular_expression) are a good fit for this
4//! problem. However, as the principles of this crate are to avoid external dependencies and
5//! maximize speed we'll instead hand code validation functions for each of the
6//! passport field criteria.
7use crate::util::iter::*;
8use crate::util::parse::*;
9use std::ops::RangeInclusive;
10
11type Input = (u32, u32);
12
13pub fn parse(input: &str) -> Input {
14    let mut passport = Vec::new();
15
16    input.split("\n\n").fold((0, 0), |(part_one, part_two), block| {
17        passport.clear();
18        passport
19            .extend(block.split([':', ' ', '\n']).chunk::<2>().filter(|&[key, _]| key != "cid"));
20
21        if passport.len() == 7 {
22            (part_one + 1, part_two + passport.iter().all(validate_field) as u32)
23        } else {
24            (part_one, part_two)
25        }
26    })
27}
28
29pub fn part1(input: &Input) -> u32 {
30    input.0
31}
32
33pub fn part2(input: &Input) -> u32 {
34    input.1
35}
36
37fn validate_field(&[key, value]: &[&str; 2]) -> bool {
38    match key {
39        "byr" => validate_range(value, 1920..=2002),
40        "iyr" => validate_range(value, 2010..=2020),
41        "eyr" => validate_range(value, 2020..=2030),
42        "hgt" => validate_height(value),
43        "hcl" => validate_hair_color(value),
44        "ecl" => validate_eye_color(value),
45        "pid" => validate_passport_id(value),
46        _ => unreachable!(),
47    }
48}
49
50fn validate_range(s: &str, range: RangeInclusive<u32>) -> bool {
51    range.contains(&s.unsigned())
52}
53
54fn validate_height(hgt: &str) -> bool {
55    if let Some(n) = hgt.strip_suffix("in") {
56        validate_range(n, 59..=76)
57    } else if let Some(n) = hgt.strip_suffix("cm") {
58        validate_range(n, 150..=193)
59    } else {
60        false
61    }
62}
63
64fn validate_hair_color(hcl: &str) -> bool {
65    let hcl = hcl.as_bytes();
66    hcl.len() == 7 && hcl[0] == b'#' && hcl[1..].iter().all(u8::is_ascii_hexdigit)
67}
68
69fn validate_eye_color(ecl: &str) -> bool {
70    matches!(ecl, "amb" | "blu" | "brn" | "gry" | "grn" | "hzl" | "oth")
71}
72
73fn validate_passport_id(pid: &str) -> bool {
74    pid.len() == 9 && pid.bytes().all(|b| b.is_ascii_digit())
75}
aoc/year2020/day04.rs

aoc/year2020/
day04.rs
