2022, day2: part 2 done

1 files changed, 39 insertions, 0 deletions

diff --git a/2022/day2/part2/src/main.rs b/2022/day2/part2/src/main.rs
new file mode 100644
index 0000000..86c893b
--- /dev/null
+++ b/2022/day2/part2/src/main.rs
@@ -0,0 +1,39 @@
+///         Rock     : 1
+///         Paper    : 2
+///         Scissors : 3
+///         opponent
+///         R   P   S
+/// me      A   B   C
+/// _ L X   3   1   2
+/// _ D Y   4   5   6
+/// _ W Z   8   9   7
+///
+/// idx = 3 * op_idx + my_idx
+const RPS_RESULTS: [usize; 9] = [3, 1, 2, 4, 5, 6, 8, 9, 7];
+
+fn main() {
+    let score = include_str!("../../input").lines().fold(0, parse_line);
+    println!("{}", score);
+}
+
+fn parse_line(score: usize, line: &str) -> usize {
+    let mut moves = line.split(' ');
+    let opponent_move = moves.next().unwrap();
+    let my_move = moves.next().unwrap();
+
+    let my_idx = match opponent_move {
+        "A" => 0,
+        "B" => 1,
+        "C" => 2,
+        _ => unreachable!(),
+    };
+
+    let op_idx = match my_move {
+        "X" => 0,
+        "Y" => 1,
+        "Z" => 2,
+        _ => unreachable!(),
+    };
+
+    RPS_RESULTS[3 * op_idx + my_idx] + score
+}