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    let mut part_one = 0;
16    let mut part_two = 0;
17
18    for block in input.split("\n\n") {
19        parse_block(&mut passport, block);
20
21        if passport.len() == 7 {
22            part_one += 1;
23            part_two += passport.iter().all(validate_field) as u32;
24        }
25
26        passport.clear();
27    }
28
29    (part_one, part_two)
30}
31
32pub fn part1(input: &Input) -> u32 {
33    input.0
34}
35
36pub fn part2(input: &Input) -> u32 {
37    input.1
38}
39
40fn parse_block<'a>(passport: &mut Vec<[&'a str; 2]>, block: &'a str) {
41    passport.extend(block.split([':', ' ', '\n']).chunk::<2>().filter(|&[key, _]| key != "cid"));
42}
43
44fn validate_field(&[key, value]: &[&str; 2]) -> bool {
45    match key {
46        "byr" => validate_range(value, 1920..=2002),
47        "iyr" => validate_range(value, 2010..=2020),
48        "eyr" => validate_range(value, 2020..=2030),
49        "hgt" => validate_height(value),
50        "hcl" => validate_hair_color(value),
51        "ecl" => validate_eye_color(value),
52        "pid" => validate_passport_id(value),
53        _ => unreachable!(),
54    }
55}
56
57fn validate_range(s: &str, range: RangeInclusive<u32>) -> bool {
58    range.contains(&s.unsigned())
59}
60
61fn validate_height(hgt: &str) -> bool {
62    if let Some(n) = hgt.strip_suffix("in") {
63        validate_range(n, 59..=76)
64    } else if let Some(n) = hgt.strip_suffix("cm") {
65        validate_range(n, 150..=193)
66    } else {
67        false
68    }
69}
70
71fn validate_hair_color(hcl: &str) -> bool {
72    let hcl = hcl.as_bytes();
73    hcl.len() == 7 && hcl[0] == b'#' && hcl[1..].iter().all(u8::is_ascii_hexdigit)
74}
75
76fn validate_eye_color(ecl: &str) -> bool {
77    matches!(ecl, "amb" | "blu" | "brn" | "gry" | "grn" | "hzl" | "oth")
78}
79
80fn validate_passport_id(pid: &str) -> bool {
81    pid.len() == 9 && pid.bytes().all(|b| b.is_ascii_digit())
82}
aoc/year2020/day04.rs

aoc/year2020/
day04.rs
