adventofcode-2020/day-4/src/main.rs

123 lines
3.4 KiB
Rust

use std::collections::HashMap;
use std::fs;
fn main() -> Result<(), Box<dyn std::error::Error>> {
let input = fs::read_to_string("input")?;
let passports = parse_passports(&input)?;
println!("{}", validate_passports(&passports));
Ok(())
}
fn parse_passports(input: &str) -> Result<Vec<HashMap<&str, &str>>, &str> {
input
.split("\n\n")
.map(|passport| {
passport
.trim()
.split(|c| c == ' ' || c == '\n')
.map(|field| {
let split = field
.find(':')
.ok_or("Invalid passport entry; no separator")?;
let item = field.split_at(split);
let key = item.0;
let value = item
.1
.strip_prefix(":")
.expect("We've already checked the separator exists");
Ok((key, value))
})
.collect()
})
.collect()
}
fn validate_passports(passports: &Vec<HashMap<&str, &str>>) -> usize {
let required_fields = ["byr", "iyr", "eyr", "hgt", "hcl", "ecl", "pid"];
let rules = [
|year: &str| match year.parse() {
Ok(1920..=2002) => true,
_ => false,
},
|year: &str| match year.parse() {
Ok(2010..=2020) => true,
_ => false,
},
|year: &str| match year.parse() {
Ok(2020..=2030) => true,
_ => false,
},
|height: &str| match height.split_at(height.chars().count() - 2) {
(height, "cm") => match height.parse() {
Ok(150..=193) => true,
_ => false,
},
(height, "in") => match height.parse() {
Ok(59..=76) => true,
_ => false,
},
_ => false,
},
|color: &str| match color.split_at(1) {
("#", code) => code.chars().all(|a| char::is_ascii_hexdigit(&a)),
_ => false,
},
|color: &str| {
["amb", "blu", "brn", "gry", "grn", "hzl", "oth"]
.iter()
.any(|c| c == &color)
},
|pid: &str| pid.chars().count() == 9 && pid.chars().all(char::is_numeric),
];
passports
.iter()
.filter(|passport| {
required_fields
.iter()
.zip(rules.iter())
.all(|(field, rule)| {
if let Some(value) = passport.get(field) {
rule(value)
} else {
false
}
})
})
.count()
}
#[cfg(test)]
mod tests {
use super::*;
use indoc::indoc;
#[test]
fn test_simple() -> Result<(), String> {
let example = indoc!(
"ecl:gry pid:860033327 eyr:2020 hcl:#fffffd
byr:1937 iyr:2017 cid:147 hgt:183cm
iyr:2013 ecl:amb cid:350 eyr:2023 pid:028048884
hcl:#cfa07d byr:1929
hcl:#ae17e1 iyr:2013
eyr:2024
ecl:brn pid:760753108 byr:1931
hgt:179cm
hcl:#cfa07d eyr:2025 pid:166559648
iyr:2011 ecl:brn hgt:59in
"
);
let passports = parse_passports(example)?;
assert_eq!(validate_passports(&passports), 2);
Ok(())
}
}