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author | June McEnroe <programble@gmail.com> | 2016-12-04 01:58:18 -0500 |
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committer | June McEnroe <programble@gmail.com> | 2016-12-04 01:58:18 -0500 |
commit | 9218d13e92158418e0d90eb0105ccb0f92c51fc0 (patch) | |
tree | e18fb2d3fcce669e6f73b13d3bfecf9183bc7c95 /src | |
parent | Day 3 part 2 (diff) | |
download | aoc-9218d13e92158418e0d90eb0105ccb0f92c51fc0.tar.gz aoc-9218d13e92158418e0d90eb0105ccb0f92c51fc0.zip |
Day 4
Diffstat (limited to 'src')
-rw-r--r-- | src/bin/day04.rs | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/src/bin/day04.rs b/src/bin/day04.rs new file mode 100644 index 0000000..9f7d0ab --- /dev/null +++ b/src/bin/day04.rs @@ -0,0 +1,78 @@ +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..])); +} |