Day 2

src/day02/input/test1.txt

@@ -0,0 +1,5 @@
+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

src/day02/mod.rs

@@ -0,0 +1,135 @@
+use std::str::FromStr;
+
+use anyhow::{anyhow, Result};
+
+use crate::instrument::instrument;
+
+const INPUT: &str = include_str!("input/input.txt");
+
+#[derive(Debug)]
+struct Handful {
+    red: u32,
+    green: u32,
+    blue: u32,
+}
+
+impl FromStr for Handful {
+    type Err = anyhow::Error;
+    fn from_str(s: &str) -> Result<Self> {
+        let mut red = 0;
+        let mut green = 0;
+        let mut blue = 0;
+        for handful in s.split(',') {
+            let mut handful = handful.trim().split(' ');
+            let num = handful
+                .next()
+                .ok_or_else(|| anyhow!("Invalid handful"))?
+                .parse()?;
+            match handful.next().ok_or_else(|| anyhow!("Invalid handful"))? {
+                "red" => red = num,
+                "green" => green = num,
+                "blue" => blue = num,
+                _ => return Err(anyhow!("Invalid handful")),
+            }
+        }
+        Ok(Self { red, green, blue })
+    }
+}
+
+#[derive(Debug)]
+struct Game {
+    id: u32,
+    handfuls: Vec<Handful>,
+}
+
+impl FromStr for Game {
+    type Err = anyhow::Error;
+    fn from_str(s: &str) -> Result<Self> {
+        let mut s = s.trim().split(':');
+        let id = s
+            .next()
+            .ok_or_else(|| anyhow!("Invalid game line: no ':' found"))?;
+        let id = id
+            .split(' ')
+            .last()
+            .ok_or_else(|| anyhow!("Invalid game line: no number found"))?
+            .parse()?;
+        let handfuls = s
+            .next()
+            .ok_or_else(|| anyhow!("Invalid game line: nothing after ':' found"))?;
+        let handfuls = handfuls
+            .split(';')
+            .map(|handful| handful.parse())
+            .collect::<Result<Vec<Handful>>>()?;
+        Ok(Self { id, handfuls })
+    }
+}
+
+fn part1(input: &str) -> Result<u32> {
+    let total_red = 12;
+    let total_green = 13;
+    let total_blue = 14;
+
+    let games = input
+        .lines()
+        .map(|line| line.parse())
+        .collect::<Result<Vec<Game>>>()?;
+    Ok(games
+        .into_iter()
+        .filter(|game| {
+            !game.handfuls.iter().any(|handful| {
+                handful.red > total_red || handful.green > total_green || handful.blue > total_blue
+            })
+        })
+        .map(|game| game.id)
+        .sum())
+}
+
+fn part2(input: &str) -> Result<u32> {
+    let games = input
+        .lines()
+        .map(|line| line.parse())
+        .collect::<Result<Vec<Game>>>()?;
+    let mut sum = 0;
+    for game in games {
+        let mut max_red = 0;
+        let mut max_green = 0;
+        let mut max_blue = 0;
+        for handful in game.handfuls {
+            if handful.red > max_red {
+                max_red = handful.red;
+            }
+            if handful.green > max_green {
+                max_green = handful.green;
+            }
+            if handful.blue > max_blue {
+                max_blue = handful.blue;
+            }
+        }
+        sum += max_red * max_green * max_blue;
+    }
+    Ok(sum)
+}
+
+pub fn solve() -> Result<()> {
+    println!("\nDay 02");
+    instrument!(part1(INPUT)?, part2(INPUT)?);
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INPUT1: &str = include_str!("input/test1.txt");
+
+    #[test]
+    fn test_part1() {
+        assert_eq!(part1(TEST_INPUT1).unwrap(), 8);
+    }
+
+    #[test]
+    fn test_part2() {
+        assert_eq!(part2(TEST_INPUT1).unwrap(), 2286);
+    }
+}

src/main.rs

@@ -1,4 +1,5 @@
 pub mod day01;
+pub mod day02;
 pub mod instrument;
 
 use anyhow::Result;
@@ -6,5 +7,6 @@ use anyhow::Result;
 fn main() -> Result<()> {
     println!("Advent of Code 2023");
     day01::solve()?;
+    day02::solve()?;
     Ok(())
 }