Solve day 2

src/bin/02.rs

@@ -0,0 +1,93 @@
+const INPUT: &str = include_str!("../../input/02");
+const TEST_INPUT: &str = include_str!("../../input/02-test");
+
+fn main() {
+    assert_eq!(part1(TEST_INPUT), 8);
+    println!("Part 1: {}", part1(INPUT));
+
+    assert_eq!(part2(TEST_INPUT), 2286);
+    println!("Part 2: {}", part2(INPUT));
+}
+
+fn part1(input: &str) -> u32 {
+    parse(input)
+        .filter(|game| game.is_possible())
+        .map(|game| game.id)
+        .sum()
+}
+
+fn part2(input: &str) -> u32 {
+    parse(input)
+        .map(|game| game.max_set())
+        .map(|set| set.power())
+        .sum()
+}
+
+struct Game {
+    id: u32,
+    revealed: Vec<Set>,
+}
+
+impl Game {
+    fn is_possible(&self) -> bool {
+        self.revealed
+            .iter()
+            .all(|set| set.r <= 12 && set.g <= 13 && set.b <= 14)
+    }
+
+    fn max_set(&self) -> Set {
+        self.revealed.iter().fold(Set::default(), |a, b| Set {
+            r: a.r.max(b.r),
+            g: a.g.max(b.g),
+            b: a.b.max(b.b),
+        })
+    }
+
+    fn parse(line: &str) -> Self {
+        let (game, revealed) = line.split_once(": ").unwrap();
+        let id = game
+            .split_ascii_whitespace()
+            .last()
+            .unwrap()
+            .parse()
+            .unwrap();
+        let revealed = revealed.split("; ").map(Set::parse).collect();
+
+        Self { id, revealed }
+    }
+}
+
+#[derive(Default)]
+struct Set {
+    r: u32,
+    g: u32,
+    b: u32,
+}
+
+impl Set {
+    fn power(&self) -> u32 {
+        self.r * self.g * self.b
+    }
+
+    fn parse(s: &str) -> Self {
+        let colors = s.split(", ");
+        let mut result = Self::default();
+
+        for color in colors {
+            let (count, color) = color.split_once(" ").unwrap();
+            let count = count.parse().unwrap();
+            match color {
+                "red" => result.r = count,
+                "green" => result.g = count,
+                "blue" => result.b = count,
+                other => panic!("unknown color: {other}"),
+            }
+        }
+
+        result
+    }
+}
+
+fn parse(input: &str) -> impl Iterator<Item = Game> + '_ {
+    input.lines().map(Game::parse)
+}