Solution for day 1

.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 = 3
+
+[[package]]
+name = "aoc"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "aoc"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/days/day_1.rs

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+use std::fs::File;
+use std::io;
+use std::io::BufRead;
+use std::io::BufReader;
+
+pub fn part1() -> io::Result<u32> {
+    let file = File::open("input/day1")?;
+    let reader = BufReader::new(file);
+
+    let mut first = true;
+    let mut previous = 0;
+    let mut count = 0;
+
+    for line in reader.lines() {
+        let num: u32 = line?.parse().unwrap();
+
+        if !first && num > previous {
+            count += 1;
+        }
+
+        previous = num;
+        first = false;
+    }
+
+    Ok(count)
+}
+
+pub fn part2() -> io::Result<u32> {
+    let file = File::open("input/day1")?;
+    let reader = BufReader::new(file);
+
+    let mut vals: [u32; 3] = [0, 0, 0];
+    let mut count = 0;
+
+    for (i, line) in reader.lines().enumerate() {
+        let num: u32 = line?.parse().unwrap();
+
+        if i < 3 {
+            vals[i] = num;
+        } else {
+            // Calculate the previous sum
+            let sum = vals[0] + vals[1] + vals[2];
+
+            // Shift the values
+            vals[0] = vals[1];
+            vals[1] = vals[2];
+            vals[2] = num;
+
+            let new_sum = vals[0] + vals[1] + vals[2];
+
+            if new_sum > sum {
+                count += 1;
+            }
+        }
+    }
+
+    Ok(count)
+}

src/days/mod.rs

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+pub mod day_1;

src/main.rs

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+mod days;
+
+fn main() {
+    // Day 1
+    println!("Day 1, part 1: {}", days::day_1::part1().unwrap());
+    println!("Day 1, part 2: {}", days::day_1::part2().unwrap());
+}