add day1

2024/Cargo.toml

@@ -1,7 +1,7 @@
 [workspace]
 resolver = "2"
 members = [
-  # "day1",
+  "day1",
   # "day2",
   # "day3",
   # "day4",

2024/day1/.gitignore

@@ -0,0 +1,19 @@
+input.txt
+flamegraph.svg
+perf.data*
+### Rust
+# Generated by Cargo
+# will have compiled files and executables
+debug/
+target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# MSVC Windows builds of rustc generate these, which store debugging information
+*.pdb
+

2024/day1/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "day1"
+authors = ["mirsella <[email protected]>"]
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+itertools = "0.13.0"
+

2024/day1/build.rs

@@ -0,0 +1,28 @@
+use std::fs::File;
+use std::io::{self, Read};
+use std::path::PathBuf;
+use std::{env, fs};
+
+fn replace_in_file(file_path: &PathBuf, old: &str, new: &str) -> io::Result<()> {
+    let mut contents = String::new();
+    File::open(file_path)?.read_to_string(&mut contents)?;
+    let new_contents = contents.replace(old, new);
+    if contents != new_contents {
+        println!("Updating {}", file_path.display());
+        fs::write(file_path, new_contents)?;
+    }
+    Ok(())
+}
+
+fn main() -> io::Result<()> {
+    let pkg_name = env::var("CARGO_PKG_NAME").unwrap();
+    replace_in_file(
+        &"../Cargo.toml".into(),
+        &format!("# \"{pkg_name}\""),
+        &format!("\"{pkg_name}\""),
+    )?;
+
+    replace_in_file(&"./Cargo.toml".into(), "\n[workspace]", "")?;
+
+    Ok(())
+}

2024/day1/src/main.rs

@@ -0,0 +1,56 @@
+use itertools::Itertools;
+
+fn part1(input: &str) -> usize {
+    let (mut a, mut b): (Vec<usize>, Vec<usize>) = input
+        .lines()
+        .map(|l| {
+            l.split_whitespace()
+                .map(|n| n.parse::<usize>().unwrap())
+                .next_tuple::<(_, _)>()
+                .unwrap()
+        })
+        .unzip();
+    a.sort_unstable();
+    b.sort_unstable();
+    a.into_iter()
+        .zip(b)
+        .map(|(a, b)| (b as isize - a as isize).unsigned_abs())
+        .sum()
+}
+fn part2(input: &str) -> usize {
+    let (a, b): (Vec<usize>, Vec<usize>) = input
+        .lines()
+        .map(|l| {
+            l.split_whitespace()
+                .map(|n| n.parse::<usize>().unwrap())
+                .next_tuple::<(_, _)>()
+                .unwrap()
+        })
+        .unzip();
+    a.into_iter()
+        .map(|va| va * b.iter().filter(|&&vb| vb == va).count())
+        .sum()
+}
+fn main() {
+    let input = include_str!("../input.txt");
+    println!("Part 1: {}", part1(input));
+    println!("Part 2: {}", part2(input));
+}
+
+#[cfg(test)]
+mod tests {
+    const INPUT: &str = "3   4
+4   3
+2   5
+1   3
+3   9
+3   3";
+    #[test]
+    fn part1() {
+        assert_eq!(super::part1(INPUT), 11);
+    }
+    #[test]
+    fn part2() {
+        assert_eq!(super::part2(INPUT), 31);
+    }
+}