Day 2

Cargo.toml

@@ -6,3 +6,7 @@ edition = "2021"
 [[bin]]
 name = "day1"
 path = "src/day1.rs"
+
+[[bin]]
+name = "day2"
+path = "src/day2.rs"

src/day1.rs

@@ -18,10 +18,7 @@ fn main() {
         .collect();
 
     println!("increased {} times", increases(&measurements));
-    println!(
-        "increased {} times",
-        increases(&convolve(&measurements))
-    );
+    println!("increased {} times", increases(&convolve(&measurements)));
 }
 
 #[test]

src/day2.rs

@@ -0,0 +1,66 @@
+use std::io::{self, BufRead};
+use std::num::ParseIntError;
+use std::str::FromStr;
+
+enum Action {
+    Forward,
+    Down,
+    Up,
+}
+
+struct Command {
+    action: Action,
+    units: usize,
+}
+
+impl FromStr for Command {
+    type Err = ParseIntError;
+
+    fn from_str(s: &str) -> Result<Command, Self::Err> {
+        let words = s.split_once(' ').unwrap();
+        let action = match words.0 {
+            "forward" => Ok(Action::Forward),
+            "down" => Ok(Action::Down),
+            "up" => Ok(Action::Up),
+            _ => Err(()),
+        };
+        let units = words.1.parse()?;
+        Ok(Command {
+            action: action.unwrap(),
+            units: units,
+        })
+    }
+}
+
+fn main() {
+    const INPUT: &'static str = include_str!("../inputs/day2.txt");
+    let commands: Vec<Command> = io::Cursor::new(INPUT)
+        .lines()
+        .map(|l| l.unwrap().parse().unwrap())
+        .collect();
+
+    let mut position = 0;
+    let mut depth = 0;
+    let mut aim = 0;
+
+    for command in commands {
+        match command.action {
+            Action::Forward => {
+                position += command.units;
+                depth += aim * command.units;
+            }
+            Action::Down => {
+                aim += command.units;
+            }
+            Action::Up => {
+                aim -= command.units;
+            }
+        }
+    }
+
+    println!(
+        "horizontal position {}, depth {}, aim {}",
+        position, depth, aim
+    );
+    println!("solution {}", position * depth);
+}