day 7 part 1

src/bin/day7.rs

@@ -0,0 +1,139 @@
+#![forbid(elided_lifetimes_in_paths, unsafe_code)]
+
+use aoc23::read;
+use chumsky::{prelude::*, text::int};
+use std::{
+	collections::{BTreeSet, HashMap},
+	fmt::{self, Debug}
+};
+
+macro_rules! cards {
+	($($ident:ident = $char:literal),+) => {
+		#[derive(Clone, Copy, Eq, Hash, PartialEq, PartialOrd, Ord)]
+		enum Card { $($ident),+ }
+
+		impl Card {
+			fn parser() -> impl Parser<char, Self, Error = Simple<char>> {
+				choice((
+					$(just($char).map(|_| Self::$ident)),+
+				))
+			}
+		}
+
+		impl Debug for Card {
+			fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+				match self {
+					$(Self::$ident => write!(f, "{}", $char)),+
+				}
+			}
+		}
+	}
+}
+
+cards! {
+	Two = '2',
+	Three = '3',
+	Four = '4',
+	Five = '5',
+	Six = '6',
+	Seven = '7',
+	Eight = '8',
+	Nine = '9',
+	Ten = 'T',
+	Junior = 'J',
+	Queen = 'Q',
+	King = 'K',
+	Ass = 'A'
+}
+
+#[derive(Debug, Eq, PartialEq, PartialOrd, Ord)]
+enum Type {
+	/// All distinct (e.g. `23456`).
+	HighCard,
+	/// One pair (e.g. `A23A4`).
+	OnePair,
+	/// Two pair (e.g. `23432`).
+	TwoPair,
+	/// Three of a kind (e.g. `TTT98`).
+	ThreeOfAKind,
+	/// Full house (e.g. `23332`).
+	FullHouse,
+	/// Four of a kind (e.g. `AA8AA`).
+	FourOfAKind,
+	/// Five of a kind (e.g. `AAAAA`).
+	FiveOfAKind
+}
+
+#[derive(Debug, Eq, PartialEq, PartialOrd, Ord)]
+struct Hand {
+	ty: Type,
+	cards: [Card; 5],
+	bid: usize
+}
+
+impl Hand {
+	fn new(cards: [Card; 5], bid: usize) -> Self {
+		let mut counts: HashMap<Card, usize> = HashMap::new();
+		for card in cards {
+			*counts.entry(card).or_default() += 1;
+		}
+
+		let ty = if counts.values().any(|c| *c == 5) {
+			Type::FiveOfAKind
+		} else if counts.values().any(|c| *c == 4) {
+			Type::FourOfAKind
+		} else if counts.values().any(|c| *c == 3) {
+			if counts.values().any(|c| *c == 2) {
+				Type::FullHouse
+			} else {
+				Type::ThreeOfAKind
+			}
+		} else {
+			let pairs = counts.values().filter(|c| **c == 2).count();
+			match pairs {
+				2 => Type::TwoPair,
+				1 => Type::OnePair,
+				0 => Type::HighCard,
+				_ => unreachable!()
+			}
+		};
+
+		Self { ty, cards, bid }
+	}
+
+	fn parser() -> impl Parser<char, Self, Error = Simple<char>> {
+		Card::parser()
+			.repeated()
+			.exactly(5)
+			.then_ignore(just(" "))
+			.then(int(10))
+			.map(|(cards, bid)| {
+				Self::new(cards.try_into().unwrap(), bid.parse().unwrap())
+			})
+	}
+}
+
+fn parser() -> impl Parser<char, Vec<Hand>, Error = Simple<char>> {
+	Hand::parser()
+		.then_ignore(just("\n"))
+		.repeated()
+		.then_ignore(end())
+}
+
+fn main() -> anyhow::Result<()> {
+	let hands = read("inputs/day7.txt", parser())?;
+	// eprintln!("{hands:?}");
+
+	let sorted: BTreeSet<&Hand> = hands.iter().collect();
+	// eprintln!("{sorted:?}");
+	println!(
+		"{}",
+		sorted
+			.into_iter()
+			.enumerate()
+			.map(|(i, hand)| (i + 1) * hand.bid)
+			.sum::<usize>()
+	);
+
+	Ok(())
+}