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| 1 | +//! [Day 4: Passport Processing](https://adventofcode.com/2020/day/4) |
| 2 | +
|
| 3 | +use std::collections::HashSet; |
| 4 | + |
| 5 | +fn validate_field(field: &str, value: &str) -> bool { |
| 6 | + match (field, value.len()) { |
| 7 | + ("byr", 4) => { |
| 8 | + let byr: u32 = value.parse().unwrap_or(0); |
| 9 | + (1920..=2002).contains(&byr) |
| 10 | + } |
| 11 | + ("iyr", 4) => { |
| 12 | + let iyr: u32 = value.parse().unwrap_or(0); |
| 13 | + (2010..=2020).contains(&iyr) |
| 14 | + } |
| 15 | + ("eyr", 4) => { |
| 16 | + let eyr: u32 = value.parse().unwrap_or(0); |
| 17 | + (2020..=2030).contains(&eyr) |
| 18 | + } |
| 19 | + ("hgt", _) => value.strip_suffix("in").map_or_else( |
| 20 | + || { |
| 21 | + value.strip_suffix("cm").map_or(false, |centimeters| { |
| 22 | + let height: u8 = centimeters.parse().unwrap_or(0); |
| 23 | + (150..=193).contains(&height) |
| 24 | + }) |
| 25 | + }, |
| 26 | + |inches| { |
| 27 | + let height: u8 = inches.parse().unwrap_or(0); |
| 28 | + (59..=76).contains(&height) |
| 29 | + }, |
| 30 | + ), |
| 31 | + ("hcl", 7) => { |
| 32 | + value.starts_with('#') |
| 33 | + && value |
| 34 | + .chars() |
| 35 | + .skip(1) |
| 36 | + .all(|c| "abcdef0123456789".contains(c)) |
| 37 | + } |
| 38 | + ("ecl", 3) => ["amb", "blu", "brn", "gry", "grn", "hzl", "oth"].contains(&value), |
| 39 | + ("pid", 9) => value.chars().all(|c| c.is_ascii_digit()), |
| 40 | + _ => false, |
| 41 | + } |
| 42 | +} |
| 43 | + |
| 44 | +struct Puzzle { |
| 45 | + data: String, |
| 46 | +} |
| 47 | + |
| 48 | +impl Puzzle { |
| 49 | + const fn new() -> Self { |
| 50 | + Self { |
| 51 | + data: String::new(), |
| 52 | + } |
| 53 | + } |
| 54 | + |
| 55 | + /// Get the puzzle input. |
| 56 | + fn configure(&mut self, path: &str) { |
| 57 | + let data = std::fs::read_to_string(path).unwrap_or_else(|_| { |
| 58 | + eprintln!("cannot read input file {path}"); |
| 59 | + std::process::exit(1); |
| 60 | + }); |
| 61 | + |
| 62 | + self.data = data; |
| 63 | + } |
| 64 | + |
| 65 | + /// Solve part one. |
| 66 | + fn part1(&self) -> u32 { |
| 67 | + let mandatory_fields: HashSet<_> = ["eyr", "iyr", "byr", "ecl", "pid", "hcl", "hgt"] |
| 68 | + .iter() |
| 69 | + .copied() |
| 70 | + .collect(); |
| 71 | + |
| 72 | + self.data |
| 73 | + .split("\n\n") |
| 74 | + .map(|record| { |
| 75 | + let mut fields = HashSet::new(); |
| 76 | + for item in record.split_ascii_whitespace() { |
| 77 | + let (field, _) = item.split_once(':').unwrap(); |
| 78 | + fields.insert(field); |
| 79 | + } |
| 80 | + u32::from(fields.is_superset(&mandatory_fields)) |
| 81 | + }) |
| 82 | + .sum() |
| 83 | + } |
| 84 | + |
| 85 | + /// Solve part two. |
| 86 | + fn part2(&self) -> u32 { |
| 87 | + let mandatory_fields: HashSet<_> = ["eyr", "iyr", "byr", "ecl", "pid", "hcl", "hgt"] |
| 88 | + .iter() |
| 89 | + .copied() |
| 90 | + .collect(); |
| 91 | + |
| 92 | + self.data |
| 93 | + .split("\n\n") |
| 94 | + .map(|record| { |
| 95 | + let mut fields = HashSet::new(); |
| 96 | + for item in record.split_ascii_whitespace() { |
| 97 | + let (field, value) = item.split_once(':').unwrap(); |
| 98 | + |
| 99 | + if validate_field(field, value) { |
| 100 | + fields.insert(field); |
| 101 | + } |
| 102 | + } |
| 103 | + u32::from(fields.is_superset(&mandatory_fields)) |
| 104 | + }) |
| 105 | + .sum() |
| 106 | + } |
| 107 | +} |
| 108 | + |
| 109 | +fn main() { |
| 110 | + let args = aoc::parse_args(); |
| 111 | + let mut puzzle = Puzzle::new(); |
| 112 | + puzzle.configure(args.path.as_str()); |
| 113 | + println!("{}", puzzle.part1()); |
| 114 | + println!("{}", puzzle.part2()); |
| 115 | +} |
| 116 | + |
| 117 | +/// Test from puzzle input |
| 118 | +#[cfg(test)] |
| 119 | +mod test { |
| 120 | + use super::*; |
| 121 | + |
| 122 | + #[test] |
| 123 | + fn test_part1() { |
| 124 | + let mut puzzle = Puzzle::new(); |
| 125 | + puzzle.configure("sample_1.txt"); |
| 126 | + assert_eq!(puzzle.part1(), 2); |
| 127 | + } |
| 128 | + |
| 129 | + #[test] |
| 130 | + fn test_part2_invalid() { |
| 131 | + let mut puzzle = Puzzle::new(); |
| 132 | + puzzle.configure("sample_3.txt"); |
| 133 | + assert_eq!(puzzle.part2(), 0); |
| 134 | + } |
| 135 | + |
| 136 | + #[test] |
| 137 | + fn test_part2_valid() { |
| 138 | + let mut puzzle = Puzzle::new(); |
| 139 | + puzzle.configure("sample_4.txt"); |
| 140 | + assert_eq!(puzzle.part2(), 4); |
| 141 | + } |
| 142 | +} |
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