day 2

Cargo.toml

@@ -7,4 +7,8 @@ edition = "2021"
 name = "day01"
 path = "src/day01/main.rs"
 
+[[bin]]
+name = "day02"
+path = "src/day02/main.rs"
+
 [dependencies]

src/day02/main.rs

@@ -0,0 +1,45 @@
+use std::io;
+
+struct Location {
+    pos: i32,
+    depth: i32,
+    aim: i32,
+}
+
+fn main() {
+    let stdin = io::stdin();
+    let mut loc = Location {
+        pos: 0,
+        depth: 0,
+        aim: 0,
+    };
+
+    loop {
+        let mut buf = String::new();
+        match stdin.read_line(&mut buf).unwrap() {
+            0 => break,
+            _ => handle_cmd(&mut loc, buf.trim())
+        }
+    }
+
+    println!("Submarine is at pos {}, depth {}", loc.pos, loc.depth);
+    println!("Answer: {}", loc.pos * loc.depth);
+}
+
+fn handle_cmd(loc: &mut Location, cmd: &str) {
+    let mut iter = cmd.split_whitespace();
+    match iter.next() {
+        Some("up") => loc.aim -= iter.next().unwrap().parse::<i32>().unwrap(),
+        Some("down") => loc.aim += iter.next().unwrap().parse::<i32>().unwrap(),
+        Some("forward") => {
+            let val = iter.next().unwrap().parse::<i32>().unwrap();
+            loc.pos += val;
+            loc.depth += val * loc.aim;
+            if loc.depth < 0 {
+                panic!("submarine attempted to fly")
+            }
+        },
+        Some(s) => panic!("unknown command \"{}\"", s),
+        None => panic!("empty command"),
+    }
+}