day 5 part 1

src/bin/day5.rs

@@ -0,0 +1,156 @@
+#![allow(clippy::let_and_return)]
+#![forbid(elided_lifetimes_in_paths, unsafe_code)]
+
+use aoc23::read;
+use chumsky::{prelude::*, text::int};
+
+struct Range {
+	source_start: usize,
+	target_start: usize,
+	len: usize
+}
+
+struct Map {
+	ranges: Vec<Range>
+}
+
+impl Map {
+	fn get(&self, source: usize) -> usize {
+		for r in &self.ranges {
+			let Some(offset) = source.checked_sub(r.source_start) else {
+				continue;
+			};
+			if offset < r.len {
+				return r.target_start + offset;
+			}
+		}
+
+		source
+	}
+
+	fn parser() -> impl Parser<char, Self, Error = Simple<char>> {
+		int(10)
+			.separated_by(just(" "))
+			.exactly(3)
+			.then_ignore(just("\n"))
+			.repeated()
+			.map(|ranges| Self {
+				ranges: ranges
+					.into_iter()
+					.map(|ints: Vec<String>| Range {
+						source_start: ints[1].parse().unwrap(),
+						target_start: ints[0].parse().unwrap(),
+						len: ints[2].parse().unwrap()
+					})
+					.collect()
+			})
+	}
+}
+
+struct Almanac {
+	seeds: Vec<usize>,
+	seed_to_soil: Map,
+	soil_to_fertilizer: Map,
+	fertilizer_to_water: Map,
+	water_to_light: Map,
+	light_to_temperature: Map,
+	temperature_to_humidity: Map,
+	humidity_to_location: Map
+}
+
+impl Almanac {
+	fn parser() -> impl Parser<char, Self, Error = Simple<char>> {
+		fn parse_another_map<'a, P, T>(
+			parser: P,
+			name: &'a str
+		) -> impl Parser<char, (T, Map), Error = Simple<char>> + 'a
+		where
+			P: Parser<char, T, Error = Simple<char>> + 'a,
+			T: 'a
+		{
+			parser
+				.then_ignore(just(name))
+				.then_ignore(just(" map:\n"))
+				.then(Map::parser())
+		}
+
+		let parser = just("seeds: ")
+			.ignore_then(int(10).separated_by(just(" ")))
+			.map(|ints: Vec<String>| {
+				ints.into_iter()
+					.map(|int| int.parse().unwrap())
+					.collect::<Vec<usize>>()
+			})
+			.then_ignore(just("\n\n"));
+		let parser = parse_another_map(parser, "seed-to-soil").then_ignore(just("\n"));
+		let parser =
+			parse_another_map(parser, "soil-to-fertilizer").then_ignore(just("\n"));
+		let parser =
+			parse_another_map(parser, "fertilizer-to-water").then_ignore(just("\n"));
+		let parser = parse_another_map(parser, "water-to-light").then_ignore(just("\n"));
+		let parser =
+			parse_another_map(parser, "light-to-temperature").then_ignore(just("\n"));
+		let parser =
+			parse_another_map(parser, "temperature-to-humidity").then_ignore(just("\n"));
+		let parser = parse_another_map(parser, "humidity-to-location");
+
+		parser.map(
+			|(
+				(
+					(
+						(
+							(
+								((seeds, seed_to_soil), soil_to_fertilizer),
+								fertilizer_to_water
+							),
+							water_to_light
+						),
+						light_to_temperature
+					),
+					temperature_to_humidity
+				),
+				humidity_to_location
+			)| {
+				Almanac {
+					seeds,
+					seed_to_soil,
+					soil_to_fertilizer,
+					fertilizer_to_water,
+					water_to_light,
+					light_to_temperature,
+					temperature_to_humidity,
+					humidity_to_location
+				}
+			}
+		)
+	}
+}
+
+fn parser() -> impl Parser<char, Almanac, Error = Simple<char>> {
+	Almanac::parser().then_ignore(end())
+}
+
+fn main() -> anyhow::Result<()> {
+	let almanac = read("inputs/day5.txt", parser())?;
+
+	let min_loc = almanac
+		.seeds
+		.iter()
+		.copied()
+		.map(|seed| {
+			let soil = almanac.seed_to_soil.get(seed);
+			let fertilizer = almanac.soil_to_fertilizer.get(soil);
+			let water = almanac.fertilizer_to_water.get(fertilizer);
+			let light = almanac.water_to_light.get(water);
+			let temperature = almanac.light_to_temperature.get(light);
+			let humidity = almanac.temperature_to_humidity.get(temperature);
+			let location = almanac.humidity_to_location.get(humidity);
+			// eprintln!("{seed}, {soil}, {fertilizer}, {water}, {light}, {temperature}, {humidity}, {location}");
+			location
+		})
+		.min()
+		.unwrap();
+	println!("{min_loc}");
+
+	Ok(())
+}