Day 1

Cargo.lock

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

Cargo.toml

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+[package]
+name = "advent"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

src/main.rs

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+use std::fs;
+
+fn main() {
+    let puzzle_input = fs::read_to_string("res/puzzle_1.txt").unwrap();
+    let (mut left, mut right): (Vec<u64>, Vec<u64>) = puzzle_input
+        .lines()
+        .filter(|line| !line.is_empty())
+        .map(|line| {
+            let nums: Vec<&str> = line.split_whitespace().collect();
+            (
+                nums[0].parse::<u64>().expect("Invalid left number"),
+                nums[1].parse::<u64>().expect("Invalid right number")
+            )
+        })
+        .unzip();
+    println!("Found {} number pairs.", left.len());
+
+    left.sort();
+    right.sort();
+
+    let differences: u64 = left.iter()
+        .zip(right.iter())
+        .map(|(a, b)| if a > b { a - b } else { b - a })
+        .sum();
+    println!("{}", differences);
+
+    let similarity: u64 = left.iter()
+        .map(|a| {
+            let occurences = right.iter().filter(|b| a == *b).count();
+            a * occurences as u64
+        })
+        .sum();
+    println!("{}", similarity);
+}