[rs] Solve 2022_10 part 1

rs/src/main.rs

@@ -41,8 +41,11 @@ macro_rules! days {
 
 impl Day {
     fn from_path(path: &Path) -> Option<Self> {
-        let day = &path.file_stem()?.as_bytes()[..7];
-        let day = String::from_utf8_lossy(day);
+        let bytes = path.file_stem()?.as_bytes();
+        if bytes.len() < 7 {
+            return None;
+        }
+        let day = String::from_utf8_lossy(&bytes[..7]);
         Self::from_str(&day).ok()
     }
 }
@@ -57,6 +60,7 @@ days! {
     Y2022D07: "2022_07" => y2022::d07::solve,
     Y2022D08: "2022_08" => y2022::d08::solve,
     Y2022D09: "2022_09" => y2022::d09::solve,
+    Y2022D10: "2022_10" => y2022::d10::solve,
 }
 
 #[derive(Parser)]

rs/src/y2022.rs

@@ -7,3 +7,4 @@ pub mod d06;
 pub mod d07;
 pub mod d08;
 pub mod d09;
+pub mod d10;

rs/src/y2022/d10.rs

@@ -0,0 +1,47 @@
+#[derive(Clone, Copy)]
+struct State {
+    x: i32,
+}
+
+struct Run {
+    history: Vec<State>,
+    now: State,
+}
+
+impl Run {
+    fn new() -> Self {
+        Self {
+            history: vec![],
+            now: State { x: 1 },
+        }
+    }
+
+    fn noop(&mut self) {
+        self.history.push(self.now);
+    }
+
+    fn addx(&mut self, arg: i32) {
+        self.noop();
+        self.noop();
+        self.now.x += arg;
+    }
+}
+
+pub fn solve(input: String) {
+    let mut run = Run::new();
+    for line in input.lines() {
+        if line == "noop" {
+            run.noop();
+        } else if let Some(arg) = line.strip_prefix("addx ") {
+            run.addx(arg.parse().unwrap());
+        } else {
+            panic!("Unknown instruction");
+        }
+    }
+
+    let part1 = [20, 60, 100, 140, 180, 220]
+        .into_iter()
+        .map(|i| run.history[i - 1].x * i as i32)
+        .sum::<i32>();
+    println!("Part 1: {part1}");
+}