1 files changed, 163 insertions, 0 deletions
diff --git a/src/day_02.rs b/src/day_02.rs
new file mode 100644
index 0000000..30607b6
--- /dev/null
+++ b/src/day_02.rs
@@ -0,0 +1,163 @@
+use std::str::FromStr;
+
+use crate::{Problem, Solution};
+
+pub struct Day02;
+
+impl Problem for Day02 {
+    const DAY: u8 = 2;
+
+    const INPUT: &'static str = include_str!("../input/day_02.txt");
+}
+
+impl Solution for Day02 {
+    type Answer1 = usize;
+
+    type Answer2 = usize;
+
+    fn part_1(input: &str) -> anyhow::Result<Self::Answer1> {
+        // only 12 red cubes, 13 green cubes, and 14 blue cubes
+        const MAX_SET: CubeSet = CubeSet {
+            red: 12,
+            green: 13,
+            blue: 14,
+        };
+
+        Ok(input
+            .trim()
+            .split('\n')
+            .map(Game::from_str)
+            .try_collect::<Vec<_>>()?
+            .iter()
+            .filter_map(|s| s.is_valid(&MAX_SET).then_some(s.id))
+            .sum())
+    }
+
+    fn part_2(input: &str) -> anyhow::Result<Self::Answer2> {
+        Ok(input
+            .trim()
+            .split('\n')
+            .map(Game::from_str)
+            .try_collect::<Vec<_>>()?
+            .into_iter()
+            .map(Game::min_set)
+            .try_collect::<Vec<_>>()?
+            .iter()
+            .map(CubeSet::power)
+            .sum())
+    }
+}
+
+#[derive(Debug, Default)]
+struct Game {
+    id: usize,
+    sets: Vec<CubeSet>,
+}
+
+impl Game {
+    fn is_valid(&self, max_set: &CubeSet) -> bool {
+        self.sets.iter().all(|c| c.is_valid(max_set))
+    }
+
+    fn min_set(self) -> Result<CubeSet, anyhow::Error> {
+        self.sets
+            .into_iter()
+            .reduce(|acc, c| c.maximize(acc))
+            .ok_or(anyhow::format_err!("No sets found in game"))
+    }
+}
+
+impl FromStr for Game {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (id, round) = s
+            .trim()
+            .split_once(':')
+            .ok_or(anyhow::format_err!("Invalid game format"))?;
+
+        let id = id
+            .strip_prefix("Game ")
+            .ok_or(anyhow::format_err!("Invalid game format"))?
+            .parse()?;
+
+        let round = round
+            .trim()
+            .split(';')
+            .map(CubeSet::from_str)
+            .collect::<Result<_, _>>()?;
+
+        Ok(Game { id, sets: round })
+    }
+}
+
+#[derive(Debug, Default)]
+struct CubeSet {
+    red: u16,
+    green: u16,
+    blue: u16,
+}
+
+impl CubeSet {
+    fn is_valid(&self, CubeSet { red, green, blue }: &CubeSet) -> bool {
+        &self.red <= red && &self.green <= green && &self.blue <= blue
+    }
+
+    fn maximize(&self, CubeSet { red, green, blue }: CubeSet) -> CubeSet {
+        CubeSet {
+            red: self.red.max(red),
+            green: self.green.max(green),
+            blue: self.blue.max(blue),
+        }
+    }
+
+    fn power(&self) -> usize {
+        (self.red * self.green * self.blue) as usize
+    }
+}
+
+impl FromStr for CubeSet {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        s.trim().split(',').try_fold(Self::default(), |mut acc, s| {
+            let (n, c) = s
+                .trim()
+                .split_once(' ')
+                .ok_or(anyhow::format_err!("Invalid cube format: {s}"))?;
+
+            let n = u16::from_str(n)?;
+            match c {
+                "red" => acc.red += n,
+                "green" => acc.green += n,
+                "blue" => acc.blue += n,
+                _ => anyhow::bail!("Invalid cube color"),
+            };
+
+            Ok(acc)
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const INPUT: &str = indoc::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 test_part_1() -> anyhow::Result<()> {
+        Ok(assert_eq!(8, Day02::part_1(INPUT)?))
+    }
+
+    #[test]
+    fn test_part_2() -> anyhow::Result<()> {
+        Ok(assert_eq!(2286, Day02::part_2(INPUT)?))
+    }
+}