Solve Part 1

src/main.rs

@@ -1,3 +1,126 @@
-fn main() {
-    println!("Hello, world!");
+// https://adventofcode.com/2022/day/2
+
+const DATA: &'static str = include_str!("input.txt");
+
+use std::str::FromStr;
+
+#[derive(PartialEq, Eq)]
+enum Move
+{
+    Rock,
+    Paper,
+    Scissors
+}
+
+#[derive(PartialEq, Eq)]
+#[repr(i32)]
+enum Outcome
+{
+    Loss = 0,
+    Draw = 3,
+    Win = 6
+}
+
+impl Outcome
+{
+    pub fn as_score(&self) -> i32
+    {
+        match self {
+            Self::Loss => 0,
+            Self::Draw => 3,
+            Self::Win => 6,
+        }
+    } 
+}
+
+impl Move
+{
+    pub fn as_score(&self) -> i32
+    {
+        match self {
+            Self::Rock => 1,
+            Self::Paper => 2,
+            Self::Scissors => 3
+        }
+    }
+
+    pub fn did_win(&self, other: &Move) -> Outcome 
+    {
+        if self == other { Outcome::Draw }
+        else {
+            match self {
+                Self::Rock => {
+                    if *other == Move::Paper { Outcome::Loss }
+                    else { Outcome::Win }
+                }
+
+                Self::Paper => {
+                    if *other == Move::Scissors { Outcome::Loss }
+                    else { Outcome::Win }
+                }
+
+                Self::Scissors => {
+                    if *other == Move::Rock { Outcome::Loss }
+                    else { Outcome::Win }
+                }
+            }
+        }
+    }
+}
+
+#[derive(Debug)]
+enum MoveParseFailure
+{
+    InvalidMove,
+}
+
+impl FromStr for Move {
+    type Err = MoveParseFailure;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "A" => Ok(Self::Rock),
+            "B" => Ok(Self::Paper),
+            "C" => Ok(Self::Scissors),
+            "X" => Ok(Self::Rock),
+            "Y" => Ok(Self::Paper),
+            "Z" => Ok(Self::Scissors),
+            _ => Err(MoveParseFailure::InvalidMove)
+        }
+    }
+}
+
+fn score_for_round(my_move: &Move, other_move: &Move) -> i32 
+{
+    let mut score = my_move.as_score();
+
+    let outcome = my_move.did_win(other_move);
+
+    score += outcome.as_score();
+
+    score
+}
+
+fn parse_round_and_get_score(round_str: &str) -> Option<i32>
+{
+    let mut moves = round_str.split(" ");
+
+    let first_move = moves.nth(0)?; // Opponent's move goes first
+    let second_move = moves.nth(0)?; // My move goes second
+
+    Some(score_for_round(&second_move.parse().expect("Expected a valid move"), 
+        &first_move.parse().expect("Expected a valid move")))
+}
+
+fn part1()
+{
+    let mut score = 0;
+    for slice in DATA.split("\n")
+    {
+        score += parse_round_and_get_score(slice).expect("Input data is not correctly structured");
+    }
+    println!("Your total score is {}", score);
+}
+
+fn main() {
+    part1();
 }