Solve day 2!

source/day_02/mod.rs

@@ -0,0 +1,98 @@
+use std::str::FromStr;
+
+use color_eyre::{
+  eyre::{eyre, Error},
+  Result,
+};
+
+pub fn solve() -> Result<()> {
+  let input_data = include_str!("../../data/day_02.txt").trim();
+  println!("Day 02 Part 1: {}", part_1(input_data)?);
+  println!("Day 02 Part 2: {}", part_2(input_data)?);
+  Ok(())
+}
+
+#[derive(Debug)]
+enum Command {
+  Forward(i32),
+  Down(i32),
+  Up(i32),
+}
+
+impl FromStr for Command {
+  type Err = Error;
+
+  fn from_str(s: &str) -> Result<Self, Self::Err> {
+    let mut split = s.split(" ");
+    let command = split
+      .next()
+      .ok_or(eyre!("Command not found in line: {}", s))?;
+    let amount = split
+      .next()
+      .ok_or(eyre!("Amount not found in line: {}", s))?
+      .parse()?;
+
+    match command {
+      "forward" => Ok(Self::Forward(amount)),
+      "down" => Ok(Self::Down(amount)),
+      "up" => Ok(Self::Up(amount)),
+      _ => unimplemented!(),
+    }
+  }
+}
+
+#[derive(Debug, Default)]
+struct Submarine {
+  aim: i32,
+  depth: i32,
+  horizontal_position: i32,
+}
+
+impl Submarine {
+  fn execute_command_1(&mut self, command: Command) {
+    match command {
+      Command::Forward(amount) => self.horizontal_position += amount,
+      Command::Down(amount) => self.depth += amount,
+      Command::Up(amount) => self.depth -= amount,
+    }
+  }
+
+  fn execute_command_2(&mut self, command: Command) {
+    match command {
+      Command::Forward(amount) => {
+        self.horizontal_position += amount;
+        self.depth += self.aim * amount;
+      }
+      Command::Down(amount) => self.aim += amount,
+      Command::Up(amount) => self.aim -= amount,
+    }
+  }
+
+  fn final_result(&self) -> i32 {
+    self.horizontal_position * self.depth
+  }
+}
+
+fn parse_commands(input: &str) -> Result<Vec<Command>> {
+  input.lines().map(Command::from_str).collect::<Result<_>>()
+}
+
+fn part_1(input: &str) -> Result<i32> {
+  let mut submarine = Submarine::default();
+
+  parse_commands(input)?
+    .into_iter()
+    .for_each(|command| submarine.execute_command_1(command));
+
+  Ok(submarine.final_result())
+}
+
+fn part_2(input: &str) -> Result<i32> {
+  let mut submarine = Submarine::default();
+
+  parse_commands(input)?
+    .into_iter()
+    .for_each(|command| submarine.execute_command_2(command));
+
+  Ok(submarine.final_result())
+}

source/main.rs

@@ -1,10 +1,12 @@
 mod day_01;
+mod day_02;
 
 fn main() -> color_eyre::Result<()> {
   color_eyre::install()?;
 
   println!("Advent of Code 2021");
   day_01::solve()?;
+  day_02::solve()?;
 
   Ok(())
 }