Complete day 2 part 1

day2/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day2"
+version = "0.1.0"

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/src/main.rs

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+use std::error::Error;
+use std::fs;
+
+#[derive(Debug, Copy, Clone)]
+enum Shape {
+    Rock,
+    Paper,
+    Scissors,
+}
+use Shape::*;
+
+impl From<char> for Shape {
+    fn from(c: char) -> Self {
+        match c {
+            'A' | 'X' => Rock,
+            'B' | 'Y' => Paper,
+            'C' | 'Z' => Scissors,
+            _ => panic!("Invalid char: {}", c),
+        }
+    }
+}
+
+impl Shape {
+    fn get_score(&self) -> u32 {
+        match self {
+            Rock => 1,
+            Paper => 2,
+            Scissors => 3,
+        }
+    }
+}
+
+fn get_outcome_score(them: Shape, you: Shape) -> u32 {
+    match (them, you) {
+        // Loss
+        (Rock, Scissors) | (Paper, Rock) | (Scissors, Paper) => 0,
+
+        // Tie
+        (Rock, Rock) | (Paper, Paper) | (Scissors, Scissors) => 3,
+
+        // Win
+        (Rock, Paper) | (Paper, Scissors) | (Scissors, Rock) => 6,
+    }
+}
+
+fn get_round_score(them: char, you: char) -> u32 {
+    let them = Shape::from(them);
+    let you = Shape::from(you);
+
+    let shape_score = you.get_score();
+    let outcome_score = get_outcome_score(them, you);
+
+    shape_score + outcome_score
+}
+
+fn get_scores(lines: Vec<&str>) -> Vec<u32> {
+    lines
+        .into_iter()
+        .map(|line| {
+            // This is trying to be too clever
+            let [them, _, you]: [char; 3] = line.chars().collect::<Vec<char>>().try_into().unwrap();
+
+            get_round_score(them, you)
+        })
+        .collect()
+}
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let file_str = fs::read_to_string("input.txt")?;
+    let lines: Vec<&str> = file_str.lines().collect();
+    let scores = get_scores(lines);
+    let total = scores
+        .into_iter()
+        .reduce(|accum, item| accum + item)
+        .unwrap();
+
+    println!("Part 1: Final score: {}", total);
+
+    Ok(())
+}