day 4 part 1

src/bin/day4.rs

@@ -0,0 +1,64 @@
+#![forbid(elided_lifetimes_in_paths, unsafe_code)]
+
+use aoc23::read;
+use chumsky::{prelude::*, text::int};
+use std::collections::HashSet;
+
+struct Card {
+	id: usize,
+	winning_nums: HashSet<usize>,
+	nums: HashSet<usize>
+}
+
+impl Card {
+	fn parser() -> impl Parser<char, Self, Error = Simple<char>> {
+		let nums = just(" ")
+			.repeated()
+			.ignore_then(int(10))
+			.separated_by(just(" "))
+			.map(|nums| {
+				nums.into_iter()
+					.map(|num: String| num.parse().unwrap())
+					.collect::<HashSet<usize>>()
+			});
+
+		just("Card")
+			.ignore_then(just(" ").repeated())
+			.ignore_then(int(10))
+			.then_ignore(just(": "))
+			.then(nums)
+			.then_ignore(just(" | "))
+			.then(nums)
+			.map(|((id, winning_nums), nums): ((String, _), _)| Self {
+				id: id.parse().unwrap(),
+				winning_nums,
+				nums
+			})
+	}
+}
+
+fn parser() -> impl Parser<char, Vec<Card>, Error = Simple<char>> {
+	Card::parser()
+		.then_ignore(just("\n"))
+		.repeated()
+		.then_ignore(end())
+}
+
+fn main() -> anyhow::Result<()> {
+	let cards = read("inputs/day4.txt", parser())?;
+
+	let mut points = 0;
+	for card in &cards {
+		let matches = card
+			.nums
+			.iter()
+			.filter(|num| card.winning_nums.contains(num))
+			.count();
+		if matches > 0 {
+			points += 1 << (matches - 1);
+		}
+	}
+	println!("{points}");
+
+	Ok(())
+}