Initial commit

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "aoc2024"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "aoc2024"
+version = "0.1.0"
+edition = "2024"
+
+authors = ["Felix Suchert <dev@felixsuchert.de>"]
+description = "My solutions to the advent of code 2024"
+license = "MIT"
+
+[dependencies]

src/main.rs

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+mod solutions;
+
+use std::env;
+use std::str::FromStr;
+
+fn main() -> std::io::Result<()> {
+    println!("Hello, world!");
+
+    let mut args = env::args();
+    if args.len() < 2 {
+        eprintln!("Usage: {} [day] ...", args.next().unwrap());
+        return Ok(());
+    }
+
+    match u8::from_str(&args.next().unwrap()) {
+        Ok(1) => solutions::day_1::run(args)?,
+        Ok(_) => eprintln!("Unknown day. Are you from the future?"),
+        Err(_) => eprintln!("Unknown day format. Use integers to specify."),
+    }
+
+    Ok(())
+}

src/solutions/day_1.rs

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+use std::env;
+use std::fs::File;
+use std::io::{BufRead, BufReader};
+use std::str::FromStr;
+
+pub fn run(mut args: env::Args) -> std::io::Result<()> {
+    let filename = args
+        .next()
+        .expect("You must provide a filename as argument");
+
+    let f = File::open(filename)?;
+    let reader = BufReader::new(f);
+
+    let mut a_list = Vec::new();
+    let mut b_list = Vec::new();
+
+    for line in reader.lines() {
+        let l = line.unwrap();
+        if l.is_empty() {
+            continue;
+        }
+
+        let mut split = l.split_whitespace();
+        a_list.push(u32::from_str(split.next().unwrap()).unwrap());
+        b_list.push(u32::from_str(split.next().unwrap()).unwrap());
+    }
+
+    a_list.sort_unstable();
+    b_list.sort_unstable();
+
+    // Task 1
+    let sum = a_list
+        .iter()
+        .zip(b_list.iter())
+        .fold(0, |acc, (a, b)| acc + a.abs_diff(*b));
+
+    println!("Sum of all differences (sorted): {sum}");
+
+    // Task 2
+    let mut similarity_score = 0;
+    let mut b_idx = 0;
+    let mut current_count = 0;
+
+    for a_item in a_list {
+        while a_item > b_list[b_idx] {
+            b_idx += 1;
+            current_count = 0;
+        }
+        if a_item == b_list[b_idx] {
+            if current_count == 0 {
+                current_count += 1;
+                while b_list[b_idx + 1] == b_list[b_idx] {
+                    current_count += 1;
+                    b_idx += 1;
+                }
+            }
+            similarity_score += a_item * current_count;
+        }
+    }
+
+    println!("Similarity Score: {similarity_score}");
+
+    Ok(())
+}

src/solutions/mod.rs

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+pub mod day_1;
+