Day 2: Cube Conundrum

rs/README.md

@@ -1,4 +1,4 @@
-# [Advent of Code 2022](https://adventofcode.com/2022)
+# [Advent of Code 2023](https://adventofcode.com/2023)
 ### my answers in [Rust](https://www.rust-lang.org/) ![Rust CI](https://github.com/ephemient/aoc2022/workflows/Rust%20CI/badge.svg)
 
 This project builds with [Cargo](https://docs.rust-lang.org/cargo).

rs/benches/criterion.rs

@@ -1,4 +1,4 @@
-use aoc2023::day1;
+use aoc2023::{day1, day2};
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
 use std::env;
 use std::fs;
@@ -19,6 +19,12 @@ fn aoc2023_bench(c: &mut Criterion) -> Result<(), io::Error> {
     g.bench_function("part 1", |b| b.iter(|| day1::part1(black_box(&data))));
     g.bench_function("part 2", |b| b.iter(|| day1::part2(black_box(&data))));
     g.finish();
+
+    let data = get_day_input(2)?;
+    let mut g = c.benchmark_group("day 2");
+    g.bench_function("part 1", |b| b.iter(|| day2::part1(black_box(&data))));
+    g.bench_function("part 2", |b| b.iter(|| day2::part2(black_box(&data))));
+    g.finish();
     Ok(())
 }
 

rs/src/day2.rs

@@ -0,0 +1,71 @@
+use std::cmp::max;
+use std::collections::BTreeMap;
+
+fn parse(data: &str) -> Vec<(u32, BTreeMap<&str, u32>)> {
+    data.lines()
+        .filter_map(|line| {
+            let line = line.strip_prefix("Game ")?;
+            let (game_id, line) = line.split_once(":")?;
+            let game_id = game_id.parse().ok()?;
+            let mut cubes = BTreeMap::<&str, u32>::new();
+            for part in line.split([',', ';']) {
+                let (count, color) = part.strip_prefix(' ')?.split_once(' ')?;
+                let count = count.parse().ok()?;
+                cubes
+                    .entry(color)
+                    .and_modify(|x| *x = max(*x, count))
+                    .or_insert(count);
+            }
+            Some((game_id, cubes))
+        })
+        .collect()
+}
+
+pub fn part1(data: &str) -> u32 {
+    parse(data)
+        .into_iter()
+        .filter_map(|(game_id, mut cubes)| {
+            if cubes.remove("red").unwrap_or(0) <= 12
+                && cubes.remove("green").unwrap_or(0) <= 13
+                && cubes.remove("blue").unwrap_or(0) <= 14
+                && cubes.is_empty()
+            {
+                Some(game_id)
+            } else {
+                None
+            }
+        })
+        .sum()
+}
+
+pub fn part2(data: &str) -> u32 {
+    parse(data)
+        .into_iter()
+        .map(|(_, cubes)| cubes.into_iter().map(|(_, count)| count).product::<u32>())
+        .sum()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use indoc::indoc;
+    use pretty_assertions::assert_eq;
+
+    static EXAMPLE: &str = indoc! {"
+        Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+        Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+        Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+        Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+        Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green
+    "};
+
+    #[test]
+    fn part1_examples() {
+        assert_eq!(8, part1(EXAMPLE));
+    }
+
+    #[test]
+    fn part2_examples() {
+        assert_eq!(2286, part2(EXAMPLE));
+    }
+}

rs/src/lib.rs

@@ -1 +1,2 @@
 pub mod day1;
+pub mod day2;

rs/src/main.rs

@@ -1,4 +1,4 @@
-use aoc2023::day1;
+use aoc2023::{day1, day2};
 use std::collections::HashSet;
 use std::env;
 use std::fs;
@@ -24,5 +24,13 @@ fn main() -> io::Result<()> {
         println!();
     }
 
+    if args.is_empty() || args.contains("2") {
+        let data = get_day_input(2)?;
+        println!("Day 2");
+        println!("{:?}", day2::part1(&data));
+        println!("{:?}", day2::part2(&data));
+        println!();
+    }
+
     Ok(())
 }