feat: solve day 1, part 1 & 2

.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.
+[[package]]
+name = "advent-of-code-2021"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "advent-of-code-2021"
+version = "0.1.0"
+authors = ["Rokas Puzonas <rokas.puz@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

README.md

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 https://adventofcode.com/2021
 
+
+## Resources
+* https://github.com/ithinuel/advent-of-code-rust/tree/2020/src/bin
+* AOC runner setup: https://github.com/johnterickson/adventofcode
+* Advent of Code 2020 blog: https://danvdk.medium.com/advent-of-code-2020-this-time-in-rust-7904559e24bc
+* Advent of Code in Rust lessons learned: https://gendignoux.com/blog/2019/08/25/rust-advent-of-code.html
+* Learning Rust via Advent of Code: https://www.forrestthewoods.com/blog/learning-rust-via-advent-of-code/
+* Learning Rust through te Advent of Code: https://bennetthardwick.com/aoc-rust-intro/
+

src/day1.rs

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+use std::fs::File;
+use std::io::prelude::*;
+
+pub fn input_from_file(filename: &str) -> Vec<u32> {
+    let mut file = File::open(filename).expect("Can't open file");
+
+    let mut contents = String::new();
+    file.read_to_string(&mut contents).expect("Oops! Can not read the file...");
+
+    return contents.split_whitespace().map(|s| s.parse::<u32>().unwrap()).collect();
+}
+
+pub fn part1(depths: &[u32]) -> u32 {
+    let mut count = 0;
+    for i in 1..depths.len()  {
+        if depths[i] > depths[i-1] {
+            count += 1;
+        }
+    }
+    return count;
+}
+
+pub fn part2(depths: &[u32]) -> u32 {
+    let mut count = 0;
+    for i in 2..depths.len()-1  {
+        if depths[i+1] > depths[i-2] {
+            count += 1;
+        }
+    }
+    return count;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn part1_example() {
+        let input = [199, 200, 208, 210, 200, 207, 240, 269, 260, 263];
+        let result = part1(&input);
+        assert_eq!(result, 7);
+    }
+
+    #[test]
+    fn part2_example() {
+        let input = [199, 200, 208, 210, 200, 207, 240, 269, 260, 263];
+        let result = part2(&input);
+        assert_eq!(result, 5);
+    }
+}
+

src/main.rs

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+mod day1;
+
+fn main() {
+    let input_filename = "input.txt";
+    let input = day1::input_from_file(input_filename);
+    let result1 = day1::part1(&input);
+    let result2 = day1::part2(&input);
+    println!("Part 1 result: {}", result1);
+    println!("Part 2 result: {}", result2);
+}
+