Day 1

.gitignore

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+/target
+input.txt

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "testing"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "testing"
+version = "0.1.0"
+edition = "2021"
+
+[profile.release]
+debug = 1
+
+[lints.clippy]
+pedantic = "warn"
+all = "warn"
+
+[dependencies]

src/main.rs

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+use std::{
+    collections::HashMap,
+    fs::File,
+    io::{BufRead, BufReader},
+};
+
+#[allow(dead_code)]
+fn day1_1() {
+    let reader = BufReader::new(File::open("input.txt").unwrap());
+    let mut a = Vec::<i32>::new();
+    let mut b = Vec::<i32>::new();
+    for line in reader.lines() {
+        let line = line.unwrap();
+        let (a1, b1) = line.trim_end().split_once("   ").unwrap();
+        a.push(a1.parse().unwrap());
+        b.push(b1.parse().unwrap());
+    }
+    a.sort_unstable();
+    b.sort_unstable();
+    let result: i32 = a.into_iter().zip(b).map(|(a, b)| (a - b).abs()).sum();
+    println!("{result}");
+}
+
+#[allow(dead_code)]
+fn day1_2() {
+    let reader = BufReader::new(File::open("input.txt").unwrap());
+    let mut a = Vec::<u32>::new();
+    let mut b = HashMap::<u32, u32>::new();
+    for line in reader.lines() {
+        let line = line.unwrap();
+        let (a1, b1) = line.trim_end().split_once("   ").unwrap();
+        a.push(a1.parse().unwrap());
+        *b.entry(b1.parse().unwrap()).or_insert(0) += 1;
+    }
+    let result: u32 = a.into_iter().map(|a| a * *b.get(&a).unwrap_or(&0)).sum();
+    println!("{result}");
+}
+
+fn main() {
+    day1_1();
+    day1_2();
+}