Cleanup

2024/rust/Cargo.toml

@@ -1,6 +1,7 @@
 [package]
 name = "aoc2024"
 version = "1.0.0"
+edition = "2021"
 
 [[bin]]
 name = "day1"

2024/rust/src/day1.rs

@@ -1,66 +1,47 @@
-use std::{collections::HashMap, iter::zip, num::ParseIntError, str::FromStr};
-
-use crate::prelude::*;
-
 mod prelude;
+pub use crate::prelude::*;
 
-fn main() {
-    Day1::show(day_input(1), day_input(1))
+fn main() -> EmptyResult {
+    let mut note: HistorianNote = day_input(1).parse()?;
+    show_answers(note.smallests_distances(), note.similarity_score());
+    Ok(())
 }
 
-struct Day1 {}
-impl Day1 {
-    fn smallests_distances(input: &str) -> i64 {
-        let mut lefts = Vec::<i64>::new();
-        let mut rights = Vec::<i64>::new();
-        for l in input.lines() {
-            let mut tokens = l.split("   ");
-            lefts.push(tokens.next().unwrap().parse().unwrap());
-            rights.push(tokens.next().unwrap().parse().unwrap());
-        }
-        lefts.sort();
-        rights.sort();
-        let mut sum = 0;
-        for (l, r) in zip(&lefts, &rights) {
-            sum += (l - r).abs();
-        }
-        sum
-    }
+struct HistorianNote {
+    left: Vec<i64>,
+    right: Vec<i64>,
+}
 
-    fn similarity_score(input: &str) -> i64 {
-        let mut lefts = Vec::<i64>::new();
-        let mut rights: HashMap<i64, i64> = HashMap::new();
-        for l in input.lines() {
+impl std::str::FromStr for HistorianNote {
+    type Err = std::num::ParseIntError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut left = Vec::<i64>::new();
+        let mut right = Vec::<i64>::new();
+        for l in s.lines() {
             let mut tokens = l.split("   ");
-            lefts.push(tokens.next().unwrap().parse().unwrap());
-            let right: i64 = tokens.next().unwrap().parse().unwrap();
-            match rights.get_mut(&right) {
-                None => {
-                    rights.insert(right, 1);
-                }
-                Some(n) => {
-                    *n += 1;
-                }
-            };
+            left.push(tokens.next().unwrap_or("").parse()?);
+            right.push(tokens.next().unwrap_or("").parse()?);
         }
-        let mut sum = 0;
-        for l in &lefts {
-            sum += (rights.get(l).unwrap_or(&0) * l)
-        }
-        sum
+        Ok(Self { left, right })
     }
 }
 
-impl AoCSolution for Day1 {
-    type Input = String;
-    type Solution = i64;
-
-    fn part1(input: Self::Input) -> Self::Solution {
-        Day1::smallests_distances(&input)
+impl HistorianNote {
+    fn smallests_distances(&mut self) -> i64 {
+        self.left.sort();
+        self.right.sort();
+        std::iter::zip(&self.left, &self.right).fold(0, |sum, (l, r)| sum + (l - r).abs())
     }
 
-    fn part2(input: Self::Input) -> Self::Solution {
-        Day1::similarity_score(&input)
+    fn similarity_score(&self) -> i64 {
+        let frequencies = self.right.iter().fold(HashMap::new(), |mut map, r| {
+            *map.entry(r).or_default() += 1;
+            map
+        });
+        self.left
+            .iter()
+            .fold(0, |sum, l| sum + frequencies.get(l).unwrap_or(&0) * l)
     }
 }
 
@@ -69,30 +50,10 @@ mod tests {
     use super::*;
 
     #[test]
-    fn test() {
-        assert_eq!(
-            Day1::part1(
-                r#"3   4
-4   3
-2   5
-1   3
-3   9
-3   3"#
-                    .into()
-            ),
-            11
-        );
-        assert_eq!(
-            Day1::part2(
-                r#"3   4
-4   3
-2   5
-1   3
-3   9
-3   3"#
-                    .into()
-            ),
-            31
-        );
+    fn test() -> EmptyResult {
+        let mut note: HistorianNote = "3   4\n4   3\n2   5\n1   3\n3   9\n3   3".parse()?;
+        assert_eq!(note.smallests_distances(), 11);
+        assert_eq!(note.similarity_score(), 31);
+        Ok(())
     }
 }

2024/rust/src/prelude.rs

@@ -1,9 +1,13 @@
+pub use std::collections::HashMap;
 pub use std::fs::File;
 pub use std::io::Read;
 
 use std::path::{Path, PathBuf};
 use std::{env, io};
 
+pub type AnyResult<T> = std::result::Result<T, Box<dyn std::error::Error>>;
+pub type EmptyResult = AnyResult<()>;
+
 #[derive(Debug)]
 enum InputFileError {
     #[allow(dead_code)]
@@ -42,29 +46,7 @@ pub fn day_input_file(day: u8) -> File {
     File::open(&f).expect(format!("Failed to open file {}", f.display()).as_str())
 }
 
-pub trait AoCSolution {
-    type Input;
-    type Solution: std::fmt::Debug + std::cmp::PartialEq + std::fmt::Display;
-
-    // Are part1 and part2 solutions _always_ the same?
-    fn part1(input: Self::Input) -> Self::Solution;
-    fn part2(input: Self::Input) -> Self::Solution;
-
-    fn show(i1: Self::Input, i2: Self::Input) {
-        println!("Part 1: {}", Self::part1(i1));
-        println!("Part 2: {}", Self::part2(i2));
-    }
-}
-
-#[cfg(test)]
-pub trait AoCSolutionTest: AoCSolution {
-    const PART1_TEST_INPUT: Self::Input;
-    const PART2_TEST_INPUT: Self::Input;
-    const PART1_TEST_RESULT: Self::Solution;
-    const PART2_TEST_RESULT: Self::Solution;
-
-    fn assert_valid() {
-        assert_eq!(Self::part1(Self::PART1_TEST_INPUT), Self::PART1_TEST_RESULT);
-        assert_eq!(Self::part2(Self::PART2_TEST_INPUT), Self::PART2_TEST_RESULT);
-    }
+pub fn show_answers<T: std::fmt::Display>(part1: T, part2: T) {
+    println!("Part 1: {}", part1);
+    println!("Part 2: {}", part2);
 }