2022: day02

aoc2022/input/day02_provided.txt

@@ -0,0 +1,3 @@
+A Y
+B X
+C Z

aoc2022/src/day02.rs

@@ -0,0 +1,202 @@
+use std::fmt::Write;
+
+use anyhow::{bail, Context, Result};
+
+const INPUT: &str = include_str!("../input/day02.txt");
+
+pub fn run() -> Result<String> {
+    let mut res = String::with_capacity(128);
+
+    writeln!(res, "part 1: {}", part1(INPUT)?)?;
+    writeln!(res, "part 2: {}", part2(INPUT)?)?;
+
+    Ok(res)
+}
+
+fn part1(input: &str) -> Result<u64> {
+    let mut score = 0;
+    for line in input.lines() {
+        let round: RoundPart1 = line.parse()?;
+        score += round.score();
+    }
+
+    Ok(score)
+}
+
+fn part2(input: &str) -> Result<u64> {
+    let mut score = 0;
+    for line in input.lines() {
+        let round: RoundPart2 = line.parse()?;
+        score += round.score();
+    }
+
+    Ok(score)
+}
+
+#[derive(Debug)]
+enum Shape {
+    Rock,
+    Paper,
+    Scissors,
+}
+
+impl std::str::FromStr for Shape {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "A" | "X" => Ok(Self::Rock),
+            "B" | "Y" => Ok(Self::Paper),
+            "C" | "Z" => Ok(Self::Scissors),
+            _ => bail!("unsupported shape encoding: {}", s),
+        }
+    }
+}
+
+impl Shape {
+    fn score(&self) -> u64 {
+        match self {
+            Self::Rock => 1,
+            Self::Paper => 2,
+            Self::Scissors => 3,
+        }
+    }
+}
+
+struct RoundPart1 {
+    opponent_move: Shape,
+    my_move: Shape,
+}
+
+impl std::str::FromStr for RoundPart1 {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (opponent_move, my_move) =
+            s.split_once(' ').context("couldn't split round on space")?;
+        let opponent_move = opponent_move.parse()?;
+        let my_move = my_move.parse()?;
+
+        Ok(Self {
+            opponent_move,
+            my_move,
+        })
+    }
+}
+
+impl RoundPart1 {
+    fn outcome(&self) -> Outcome {
+        match (&self.opponent_move, &self.my_move) {
+            (Shape::Rock, Shape::Rock) => Outcome::Draw,
+            (Shape::Rock, Shape::Paper) => Outcome::Won,
+            (Shape::Rock, Shape::Scissors) => Outcome::Lost,
+            (Shape::Paper, Shape::Rock) => Outcome::Lost,
+            (Shape::Paper, Shape::Paper) => Outcome::Draw,
+            (Shape::Paper, Shape::Scissors) => Outcome::Won,
+            (Shape::Scissors, Shape::Rock) => Outcome::Won,
+            (Shape::Scissors, Shape::Paper) => Outcome::Lost,
+            (Shape::Scissors, Shape::Scissors) => Outcome::Draw,
+        }
+    }
+
+    fn score(&self) -> u64 {
+        self.outcome().score() + self.my_move.score()
+    }
+}
+
+struct RoundPart2 {
+    opponent_move: Shape,
+    outcome: Outcome,
+}
+
+impl std::str::FromStr for RoundPart2 {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (opponent_move, outcome) =
+            s.split_once(' ').context("couldn't split round on space")?;
+        let opponent_move = opponent_move.parse()?;
+        let outcome = outcome.parse()?;
+
+        Ok(Self {
+            opponent_move,
+            outcome,
+        })
+    }
+}
+
+impl RoundPart2 {
+    fn shape_to_play(&self) -> Shape {
+        match (&self.opponent_move, &self.outcome) {
+            (Shape::Rock, Outcome::Lost) => Shape::Scissors,
+            (Shape::Rock, Outcome::Draw) => Shape::Rock,
+            (Shape::Rock, Outcome::Won) => Shape::Paper,
+            (Shape::Paper, Outcome::Lost) => Shape::Rock,
+            (Shape::Paper, Outcome::Draw) => Shape::Paper,
+            (Shape::Paper, Outcome::Won) => Shape::Scissors,
+            (Shape::Scissors, Outcome::Lost) => Shape::Paper,
+            (Shape::Scissors, Outcome::Draw) => Shape::Scissors,
+            (Shape::Scissors, Outcome::Won) => Shape::Rock,
+        }
+    }
+
+    fn score(&self) -> u64 {
+        self.outcome.score() + self.shape_to_play().score()
+    }
+}
+
+enum Outcome {
+    Lost,
+    Draw,
+    Won,
+}
+
+impl std::str::FromStr for Outcome {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "X" => Ok(Self::Lost),
+            "Y" => Ok(Self::Draw),
+            "Z" => Ok(Self::Won),
+            _ => bail!("unsupported outcome encoding: {}", s),
+        }
+    }
+}
+
+impl Outcome {
+    fn score(&self) -> u64 {
+        match self {
+            Self::Lost => 0,
+            Self::Draw => 3,
+            Self::Won => 6,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const PROVIDED: &str = include_str!("../input/day02_provided.txt");
+
+    #[test]
+    fn part1_provided() {
+        assert_eq!(part1(PROVIDED).unwrap(), 15);
+    }
+
+    #[test]
+    fn part1_real() {
+        assert_eq!(part1(INPUT).unwrap(), 11150);
+    }
+
+    #[test]
+    fn part2_provided() {
+        assert_eq!(part2(PROVIDED).unwrap(), 12);
+    }
+
+    #[test]
+    fn part2_real() {
+        assert_eq!(part2(INPUT).unwrap(), 8295);
+    }
+}

aoc2022/src/lib.rs

@@ -1,3 +1,4 @@
 #![warn(clippy::explicit_iter_loop, clippy::redundant_closure_for_method_calls)]
 
 pub mod day01;
+pub mod day02;

aoc2022/src/main.rs

@@ -3,9 +3,10 @@ use anyhow::Result;
 use aoc::DayFunc;
 
 use aoc2022::day01;
+use aoc2022::day02;
 
 fn main() -> Result<()> {
-    let days: &[DayFunc] = &[day01::run];
+    let days: &[DayFunc] = &[day01::run, day02::run];
 
     aoc::run(days)
 }