2022 - Day 2

2022/input/2/test-1

@@ -0,0 +1,3 @@
+A Y
+B X
+C Z

2022/src/bin/day2.rs

@@ -0,0 +1,141 @@
+// -- Setup & Runners --
+use aoc::Solver;
+pub struct Day;
+fn main() {
+    Day::solve();
+}
+#[test]
+fn part1_test1() {
+    Day::test(aoc::Part::ONE, "test-1", 15);
+}
+#[test]
+fn part2_test1() {
+    Day::test(aoc::Part::TWO, "test-1", 12);
+}
+#[test]
+fn part1_solution() {
+    Day::test(aoc::Part::ONE, "input", 14264);
+}
+#[test]
+fn part2_solution() {
+    Day::test(aoc::Part::TWO, "input", 12382);
+}
+
+// -- Implementation for hand --
+#[derive(Debug, Copy, Clone)]
+enum Hand {
+    Rock = 0,
+    Paper = 1,
+    Scissors = 2,
+}
+
+impl Hand {
+    // Return hand that this hand loses to
+    fn loses(&self) -> Hand {
+        // Returns the next enum (cyclical) as that one always loses from the current one
+        Hand::from((u8::from(self) + 1) % 3)
+    }
+
+    // Return hand that this hand wins from
+    fn wins(&self) -> Hand {
+        // Returns the previous enum (cyclical) as that one always wins from the current one
+        Hand::from((i8::from(self) - 1).rem_euclid(3) as u8)
+    }
+
+    fn strategy(&self, input: char) -> Hand {
+        match input {
+            'X' => self.wins(),
+            'Y' => *self,
+            'Z' => self.loses(),
+            _ => panic!("Unexpected input")
+        }
+    }
+
+    // Check if we win against the other hand
+    fn play(&self, other: &Hand) -> u32 {
+        // 1 = draw, 2 = wins, 0 = loses (x3 to get the score
+        ((i8::from(self) - i8::from(other) + 1).rem_euclid(3) * 3) as u32
+    }
+
+    // Get the score value of the current hand
+    fn value(&self) -> u32 {
+        u8::from(self) as u32 + 1
+    }
+}
+
+// -- Conversions --
+impl From<u8> for Hand {
+    fn from(value: u8) -> Self {
+        match value {
+            x if x == Hand::Rock as u8 => Hand::Rock,
+            x if x == Hand::Paper as u8 => Hand::Paper,
+            x if x == Hand::Scissors as u8 => Hand::Scissors,
+            x => panic!("Unknown input: {}", x)
+        }
+    }
+}
+
+impl From<char> for Hand {
+    fn from(value: char) -> Self {
+        match value {
+            'A' | 'X' => Self::Rock,
+            'B' | 'Y' => Self::Paper,
+            'C' | 'Z' => Self::Scissors,
+            value => panic!("Unknown input: {value}"),
+        }
+    }
+}
+
+impl From<&Hand> for i8 {
+    fn from(value: &Hand) -> Self {
+        *value as Self
+    }
+}
+
+impl From<&Hand> for u8 {
+    fn from(value: &Hand) -> Self {
+        *value as Self
+    }
+}
+
+impl From<Hand> for u8 {
+    fn from(value: Hand) -> Self {
+        value as Self
+    }
+}
+
+// -- Helper functions --
+// Convert the round to a tuple containing the actions of both players
+fn round_to_letters(round: &str) -> (char, char) {
+    if let &[a, _, b] = round.as_bytes() {
+        (a as char, b as char)
+    } else {
+        panic!("Unexpected input");
+    }
+}
+
+// -- Solution --
+impl aoc::Solver for Day {
+    fn day() -> u8 {
+        2
+    }
+
+    fn part1(input: &str) -> u32 {
+        input.split("\n")
+            .filter(|round| round.len() > 0)
+            .map(round_to_letters)
+            .map(|(a, b)| (Hand::from(a), Hand::from(b)))
+            .map(|(a, b)| b.play(&a) + b.value())
+            .sum()
+    }
+
+    fn part2(input: &str) -> u32 {
+        input.split("\n")
+            .filter(|round| round.len() > 0)
+            .map(round_to_letters)
+            .map(|(a, b)| (Hand::from(a), b))
+            .map(|(a, b)| (a, a.strategy(b)))
+            .map(|(a, b)| b.play(&a) + b.value())
+            .sum()
+    }
+}