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use std::io::{self, Read};
use std::str::FromStr;
struct Room {
name: String,
sector_id: u32,
checksum: String,
}
impl FromStr for Room {
type Err = ();
fn from_str(s: &str) -> Result<Self, ()> {
let mut iter = s.trim_right_matches(']')
.rsplitn(3, |c| c == '-' || c == '[');
let checksum = iter.next().ok_or(())?;
let sector_id = iter.next().ok_or(())?;
let name = iter.next().ok_or(())?;
Ok(Room {
name: name.into(),
sector_id: sector_id.parse().map_err(|_| ())?,
checksum: checksum.into(),
})
}
}
impl Room {
fn real(&self) -> bool {
let mut letters = [
(0, 'a'), (0, 'b'), (0, 'c'), (0, 'd'), (0, 'e'), (0, 'f'), (0, 'g'), (0, 'h'),
(0, 'i'), (0, 'j'), (0, 'k'), (0, 'l'), (0, 'm'), (0, 'n'), (0, 'o'), (0, 'p'),
(0, 'q'), (0, 'r'), (0, 's'), (0, 't'), (0, 'u'), (0, 'v'), (0, 'w'), (0, 'x'),
(0, 'y'), (0, 'z'),
];
for letter in self.name.chars().filter(|c| c.is_alphabetic()) {
let index = letter as u8 - b'a';
letters[index as usize].0 -= 1;
}
letters.sort();
let expected: String = letters.into_iter()
.map(|l| l.1)
.take(5)
.collect();
expected == self.checksum
}
}
fn solve(input: &str) -> u32 {
input.lines()
.map(str::parse)
.map(Result::unwrap)
.filter(Room::real)
.map(|room| room.sector_id)
.sum()
}
fn main() {
let mut input = String::new();
io::stdin().read_to_string(&mut input).unwrap();
println!("Part 1: {}", solve(&input));
}
#[test]
fn part1() {
let input = "
aaaaa-bbb-z-y-x-123[abxyz]
a-b-c-d-e-f-g-h-987[abcde]
not-a-real-room-404[oarel]
totally-real-room-200[decoy]
";
assert_eq!(1514, solve(&input[1..]));
}
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