2021 day 2 rust

2021/rust/Cargo.lock

@@ -2,6 +2,41 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "aho-corasick"
+version = "0.7.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cc936419f96fa211c1b9166887b38e5e40b19958e5b895be7c1f93adec7071ac"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "memchr"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
+
+[[package]]
+name = "regex"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e076559ef8e241f2ae3479e36f97bd5741c0330689e217ad51ce2c76808b868a"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.6.28"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "456c603be3e8d448b072f410900c09faf164fbce2d480456f50eea6e25f9c848"
+
 [[package]]
 name = "rust"
 version = "0.1.0"
+dependencies = [
+ "regex",
+]

2021/rust/Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+regex = "1"

2021/rust/inputs/scratch.txt

@@ -0,0 +1,6 @@
+forward 5
+down 5
+forward 8
+up 3
+down 8
+forward 2

2021/rust/src/main.rs

@@ -3,5 +3,5 @@ mod solutions;
 
 
 fn main() {
-    solutions::day01::run();
+    solutions::day02::run();
 }

2021/rust/src/solutions/day01.rs

@@ -1,9 +1,9 @@
 use crate::utils;
-use crate::utils::Day;
+use crate::utils::Source;
 
 
 pub fn run() -> () {
-    let data = parse_data(utils::read_lines(Day(1)));
+    let data = parse_data(utils::read_lines(Source::Day(1)));
 
     println!("Day 1");
     println!("Part 1: {}", solve1(&data));
@@ -40,4 +40,4 @@ fn parse_data(lines: Vec<String>) -> Vec<i32> {
         .map(|x| x.parse())
         .collect::<Result<Vec<i32>, _>>()
         .expect("Failed to parse int")
-}
+}

2021/rust/src/solutions/day02.rs

@@ -0,0 +1,58 @@
+use regex::{Captures, Regex};
+use crate::utils;
+use crate::utils::Source;
+
+
+pub fn run() -> () {
+    let data = parse_data(utils::read_lines(Source::Day(2)));
+
+    println!("Day 2");
+    println!("Part 1: {}", solve1(&data));
+    println!("Part 2: {}", solve2(&data));
+}
+
+enum Command {
+    Forward(i32),
+    Down(i32),
+    Up(i32),
+}
+
+fn solve1(lines: &Vec<Command>) -> i32 {
+    let (x, depth) = lines.iter()
+        .fold((0, 0), |(x, depth), next| match next {
+            Command::Forward(val) => (x + val, depth),
+            Command::Down(val) => (x, depth + val),
+            Command::Up(val) => (x, depth - val),
+        });
+    x * depth
+}
+
+fn solve2(lines: &Vec<Command>) -> i32 {
+    let (x, depth, aim) = lines.iter()
+        .fold((0, 0, 0), |(x, depth, aim), next| match next {
+            Command::Forward(val) => (x + val, depth + (aim * val), aim),
+            Command::Down(val) => (x, depth, aim + val),
+            Command::Up(val) => (x, depth, aim - val),
+        });
+    x * depth
+}
+
+fn parse_data(lines: Vec<String>) -> Vec<Command> {
+    let re = Regex::new(r"^(\w+) (\d+)$").unwrap();
+
+    lines.iter()
+        .map(|line| re.captures(line).unwrap())
+        .map(to_command)
+        .collect::<Vec<_>>()
+}
+
+fn to_command(cap: Captures) -> Command {
+    let left = cap.get(1).unwrap().as_str();
+    let right = cap.get(2).unwrap().as_str().parse().unwrap();
+    match left {
+        "forward" => Command::Forward(right),
+        "up" => Command::Up(right),
+        "down" => Command::Down(right),
+        _ => panic!("Unknown command")
+    }
+}

2021/rust/src/solutions/mod.rs

@@ -1 +1,2 @@
 pub mod day01;
+pub mod day02;

2021/rust/src/utils.rs

@@ -3,14 +3,18 @@ use std::io::{BufRead, BufReader};
 use std::path::Path;
 
 
-#[repr(transparent)]
-pub struct Day(pub i32);
+pub enum Source { Scratch, Day(i32) }
 
 
-pub fn read_lines(day: Day) -> Vec<String> {
-    assert!(1 <= day.0 && day.0 < 25);
-    _read_lines(format!("inputs/day{:0>2}.txt", day.0))
-        .expect(format!("Failed to load day {}", day.0).as_str())
+pub fn read_lines(source: Source) -> Vec<String> {
+    let path = match source {
+        Source::Scratch => "inputs/scratch.txt".to_string(),
+        Source::Day(day) => {
+            assert!(1 <= day && day < 25);
+            format!("inputs/day{:0>2}.txt", day)
+        }
+    };
+    _read_lines(&path).expect(format!("Failed to load from {}", &path).as_str())
 }
 
 fn _read_lines<P>(filename: P) -> std::io::Result<Vec<String>>