day 2 complete

src/day2.rs

@@ -0,0 +1,110 @@
+use itertools::Itertools;
+use std::fs;
+
+pub fn run() {
+    println!("Day 2:");
+    let input = fs::read_to_string("./inputs/day2.txt").expect("Could not read file");
+
+    println!("\tPart 1: {}", part1(&input));
+    println!("\tPart 2: {}", part2(&input));
+}
+
+#[derive(PartialEq, Clone, Copy)]
+enum Hand {
+    Rock = 1,
+    Paper,
+    Scissors,
+}
+
+#[derive(Clone, Copy)]
+enum Outcome {
+    Lost = 0,
+    Draw = 3,
+    Win = 6,
+}
+
+fn part1(input: &str) -> usize {
+    input
+        .trim()
+        .split('\n')
+        .map(|round_str| {
+            let round = round_str.split_once(' ').unwrap();
+            let opponent = match round.0 {
+                "A" => Hand::Rock,
+                "B" => Hand::Paper,
+                "C" => Hand::Scissors,
+                _ => panic!(),
+            };
+            let me = match round.1 {
+                "X" => Hand::Rock,
+                "Y" => Hand::Paper,
+                "Z" => Hand::Scissors,
+                _ => panic!(),
+            };
+
+            let outcome = match (opponent, me) {
+                (l, r) if l == r => Outcome::Draw,
+                (Hand::Rock, Hand::Paper) => Outcome::Win,
+                (Hand::Paper, Hand::Scissors) => Outcome::Win,
+                (Hand::Scissors, Hand::Rock) => Outcome::Win,
+                _ => Outcome::Lost,
+            };
+            outcome as usize + me as usize
+        })
+        .sum()
+}
+fn part2(input: &str) -> usize {
+    input
+        .trim()
+        .split('\n')
+        .map(|round_str| {
+            let round = round_str.split_once(' ').unwrap();
+            let opponent = match round.0 {
+                "A" => Hand::Rock,
+                "B" => Hand::Paper,
+                "C" => Hand::Scissors,
+                _ => panic!(),
+            };
+            let outcome = match round.1 {
+                "X" => Outcome::Lost,
+                "Y" => Outcome::Draw,
+                "Z" => Outcome::Win,
+                _ => panic!(),
+            };
+
+            let me = match (outcome, opponent) {
+                (Outcome::Draw, _) => opponent,
+                (Outcome::Win, Hand::Rock) => Hand::Paper,
+                (Outcome::Win, Hand::Paper) => Hand::Scissors,
+                (Outcome::Win, Hand::Scissors) => Hand::Rock,
+                (Outcome::Lost, Hand::Rock) => Hand::Scissors,
+                (Outcome::Lost, Hand::Paper) => Hand::Rock,
+                (Outcome::Lost, Hand::Scissors) => Hand::Paper,
+            };
+            outcome as usize + me as usize
+        })
+        .sum()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1() {
+        let input = "A Y
+B X
+C Z";
+
+        assert_eq!(part1(input), 15);
+    }
+
+    #[test]
+    fn test_2() {
+        let input = "A Y
+B X
+C Z";
+
+        assert_eq!(part2(input), 12);
+    }
+}

src/main.rs

@@ -1,5 +1,7 @@
 mod day1;
+mod day2;
 fn main() {
     println!("Running Advent of Code 2022");
     day1::run();
+    day2::run();
 }