day 2

day2/Cargo.toml

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+[package]
+name = "day2"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day2/sample_input.txt

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+A Y
+B X
+C Z

day2/src/main.rs

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+#[derive(PartialEq)]
+#[repr(u8)]
+enum Move {
+    ROCK = 1,
+    PAPER = 2,
+    SCISSORS = 3
+}
+
+#[repr(u8)]
+enum Outcome {
+    LOSS = 0,
+    DRAW = 3,
+    WIN = 6
+}
+
+impl TryFrom<char> for Move {
+    type Error = ();
+
+    fn try_from(c: char) -> Result<Self, Self::Error> {
+        match c {
+            'A' | 'X' => Ok(Move::ROCK),
+            'B' | 'Y' => Ok(Move::PAPER),
+            'C' | 'Z' => Ok(Move::SCISSORS),
+            _ => Err(()),
+        }
+    }
+}
+
+impl std::fmt::Display for Move {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Move::ROCK => f.write_str("Rock").unwrap(),
+            Move::PAPER => f.write_str("Paper").unwrap(),
+            Move::SCISSORS => f.write_str("Scissors").unwrap(),
+        };
+
+        std::fmt::Result::Ok(())
+    }
+}
+
+
+
+fn main() {
+    const INPUT: &str = include_str!("../input.txt");
+
+
+    let mut your_score: u64 = 0;
+    let mut their_score: u64 = 0;
+
+    let lines = INPUT.split("\n");
+    for line in lines {
+        let mut tokens = line.split(' ');
+
+        let their_move = tokens.next().unwrap();
+        let your_move = tokens.next().unwrap();
+
+        let their_move = Move::try_from(their_move.chars().next().unwrap()).unwrap();
+        let your_move = Move::try_from(your_move.chars().next().unwrap()).unwrap();
+
+        let outcome: Outcome;
+        if their_move == your_move {
+            outcome = Outcome::DRAW
+        }
+        else if their_move == Move::ROCK {
+            outcome = if your_move == Move::PAPER { Outcome::WIN } else { Outcome::LOSS };
+        }
+        else if their_move == Move::PAPER {
+            outcome = if your_move == Move::SCISSORS { Outcome::WIN } else { Outcome::LOSS };
+        }
+        else {
+            outcome = if your_move == Move::ROCK { Outcome::WIN } else { Outcome::LOSS };
+        }
+
+        let outcome: u64 = outcome as u64;
+        your_score += outcome;
+        their_score += 6 - (outcome);
+
+        let your_move: u64 = your_move as u64;
+        let their_move: u64 = their_move as u64;
+        your_score += your_move;
+        their_score += their_move;
+    }
+
+    println!("Your score: {your_score}");
+    println!("Their score: {their_score}");
+}