Day 2, part 1

src/main.rs

@@ -2,6 +2,7 @@ use std::io;
 
 use argh::FromArgs;
 
+mod pilot;
 mod sonar;
 
 #[derive(FromArgs)]
@@ -15,6 +16,7 @@ struct Arguments {
 #[argh(subcommand)]
 enum SubCommand {
     Sonar(SonarTracker),
+    Pilot(SubPilot),
 }
 
 #[derive(FromArgs)]
@@ -30,6 +32,15 @@ struct SonarTracker {
     window: usize,
 }
 
+#[derive(FromArgs)]
+/// pilot the sub!
+#[argh(subcommand, name = "pilot")]
+struct SubPilot {
+    /// path to input data file
+    #[argh(positional)]
+    input: String,
+}
+
 fn main() -> io::Result<()> {
     let args: Arguments = argh::from_env();
     match args.command {
@@ -37,6 +48,11 @@ fn main() -> io::Result<()> {
             let count_incr = sonar::count_increases(&args.input, args.window)?;
             println!("number of increases: {}", count_incr);
         }
+        SubCommand::Pilot(args) => {
+            let pos = pilot::track_position(&args.input)?;
+            println!("Final Position: {},{}", pos.linear, pos.depth);
+            println!("Product: {}", pos.linear * pos.depth);
+        }
     }
     Ok(())
 }

src/pilot.rs

@@ -0,0 +1,45 @@
+use std::fs::File;
+use std::io;
+use std::io::prelude::*;
+
+pub struct Position {
+    pub linear: i32,
+    pub depth: i32,
+}
+
+pub fn track_position(filename: &str) -> io::Result<Position> {
+    let f = File::open(filename)?;
+    let buf = io::BufReader::new(f);
+    let mut pos = Position {
+        linear: 0,
+        depth: 0,
+    };
+    for line in buf.lines() {
+        if let Ok(line) = line {
+            let mut parts = line.split_whitespace();
+            if let Some(op) = parts.next() {
+                if let Some(value) = parts.next() {
+                    if let Ok(value) = i32::from_str_radix(value, 10) {
+                        match op {
+                            "forward" => {
+                                pos.linear += value;
+                            }
+                            "down" => {
+                                pos.depth += value;
+                            }
+                            "up" => {
+                                pos.depth -= value;
+                            }
+                            _ => {
+                                eprintln!("Invalid operation: {}", op);
+                            }
+                        }
+                    } else {
+                        eprintln!("Invalid value: {}", value);
+                    }
+                }
+            }
+        }
+    }
+    Ok(pos)
+}