initial commit

1 files changed, 105 insertions, 0 deletions

diff --git a/2022/src/day02.rs b/2022/src/day02.rs
new file mode 100644
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--- /dev/null
+++ b/2022/src/day02.rs
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+mod utils;
+
+use utils::read_input;
+
+fn main() {
+    let input = read_input();
+
+    let turns_both_moves: Vec<_> = input
+        .lines()
+        .map(|xs| {
+            let mut parts = xs.split(' ').take(2).map(Move::parse);
+            (parts.next().unwrap(), parts.next().unwrap())
+        })
+        .collect();
+
+    let total_score_p1: usize = turns_both_moves
+        .iter()
+        .map(|(them, us)| score(*them, *us))
+        .sum();
+
+    let total_score_p2: usize = turns_both_moves
+        .into_iter()
+        .map(|(them, us)| (them, us.to_outcome()))
+        .map(|(them, outcome)| (them, them.to_get(outcome)))
+        .map(|(them, us)| score(them, us))
+        .sum();
+
+    println!("Part 1: {}", total_score_p1);
+    println!("Part 2: {}", total_score_p2);
+}
+
+fn score(them: Move, us: Move) -> usize {
+    let won_val = match (them.beats(us), us.beats(them)) {
+        (true, false) => 0,
+        (false, true) => 6,
+        (false, false) => 3,
+        (a, b) => unreachable!("they beat us: {}, we beat them: {}", a, b),
+    };
+    us.value() + won_val
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Move {
+    Rock,
+    Paper,
+    Scissors,
+}
+
+impl Move {
+    fn parse(inp: &str) -> Self {
+        match inp {
+            "A" => Move::Rock,
+            "B" => Move::Paper,
+            "C" => Move::Scissors,
+            "X" => Move::Rock,
+            "Y" => Move::Paper,
+            "Z" => Move::Scissors,
+            _ => panic!("unrecognised move: {}", inp),
+        }
+    }
+
+    fn to_outcome(self) -> Outcome {
+        match self {
+            Move::Rock => Outcome::Lose,
+            Move::Paper => Outcome::Draw,
+            Move::Scissors => Outcome::Win,
+        }
+    }
+
+    fn beats(self, other: Move) -> bool {
+        matches!(
+            (self, other),
+            (Move::Paper, Move::Rock)
+                | (Move::Rock, Move::Scissors)
+                | (Move::Scissors, Move::Paper)
+        )
+    }
+
+    fn to_get(self, outcome: Outcome) -> Self {
+        match (self, outcome) {
+            (_, Outcome::Draw) => self,
+            (Move::Rock, Outcome::Win) => Move::Paper,
+            (Move::Paper, Outcome::Win) => Move::Scissors,
+            (Move::Scissors, Outcome::Win) => Move::Rock,
+            (Move::Rock, Outcome::Lose) => Move::Scissors,
+            (Move::Paper, Outcome::Lose) => Move::Rock,
+            (Move::Scissors, Outcome::Lose) => Move::Paper,
+        }
+    }
+
+    fn value(self) -> usize {
+        match self {
+            Move::Rock => 1,
+            Move::Paper => 2,
+            Move::Scissors => 3,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Outcome {
+    Win,
+    Draw,
+    Lose,
+}