Day 2, puzzle 1

src/bin/d2p1.rs

@@ -0,0 +1,9 @@
+use aoc22::day2;
+use aoc22::util;
+
+pub fn main() {
+    let rounds = day2::parse_rounds(&util::parse_input());
+
+    let score = rounds.iter().map(day2::Round::score).sum::<u32>();
+    println!("Total score is {}", score);
+}

src/day2.rs

@@ -0,0 +1,84 @@
+#[derive(PartialEq, Debug)]
+pub enum Choice {
+    Rock,
+    Paper,
+    Scissors,
+}
+
+impl Choice {
+    pub fn score(&self) -> u32 {
+        match self {
+            Choice::Rock => 1,
+            Choice::Paper => 2,
+            Choice::Scissors => 3,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Round {
+    opponent: Choice,
+    own: Choice,
+}
+
+pub enum RoundResult {
+    Win,
+    Draw,
+    Loss,
+}
+
+impl Round {
+    pub fn result(&self) -> RoundResult {
+        let win = match self.own {
+            Choice::Rock => Choice::Scissors,
+            Choice::Paper => Choice::Rock,
+            Choice::Scissors => Choice::Paper,
+        };
+
+        if self.opponent == win {
+            RoundResult::Win
+        } else if self.opponent == self.own {
+            RoundResult::Draw
+        } else {
+            RoundResult::Loss
+        }
+    }
+
+    pub fn score(&self) -> u32 {
+        let choice_score = self.own.score();
+        let result_score = match self.result() {
+            RoundResult::Win => 6,
+            RoundResult::Draw => 3,
+            RoundResult::Loss => 0,
+        };
+
+        choice_score + result_score
+    }
+}
+
+pub fn parse_choice(choice_str: &str) -> Choice {
+    match choice_str.chars().next().unwrap() {
+        'A' => Choice::Rock,
+        'B' => Choice::Paper,
+        'C' => Choice::Scissors,
+        'X' => Choice::Rock,
+        'Y' => Choice::Paper,
+        'Z' => Choice::Scissors,
+        _ => panic!("Unknown choice {}", choice_str),
+    }
+}
+
+pub fn parse_rounds(input: &String) -> Vec<Round> {
+    let lines = input.lines();
+    let mut rounds = Vec::new();
+
+    for line in lines {
+        let (opponent, own) = line.split_once(' ').unwrap();
+        rounds.push(Round {
+            opponent: parse_choice(opponent),
+            own: parse_choice(own),
+        });
+    }
+
+    rounds
+}

src/lib.rs

@@ -1,2 +1,3 @@
 pub mod day1;
+pub mod day2;
 pub mod util;