--- title: 'Advent of Code 2021 Day 1' url: 'https://blog.philippludewig.de/de/writing/advent-of-code-2021-day-1' markdown: 'https://blog.philippludewig.de/de/writing/advent-of-code-2021-day-1.md' lang: de date: '2021-12-02' description: "Aloha people, it's the time of the year again where coding elves earn some internet points and learn cool stuff while doing that. Ofc I am talking about advent of code. This year I want to use a recently learned language and re-visit some I haven't used in a while. I also try to pair with some col…" taxonomy: category: - blog - '2021' - Coding tag: - 'advent of code' --- # Advent of Code 2021 Day 1 Aloha people, it's the time of the year again where coding elves earn some internet points and learn cool stuff while doing that. Ofc I am talking about [advent of code](https://adventofcode.com/). This year I want to use a recently learned language and re-visit some I haven't used in a while. I also try to pair with some colleagues on the puzzles as I am still on the beach and this are the perfect coding exercises between the cloud provider workshops. In these years advent of code the story starts with a careless elf who has dropped the sleigh keys into the ocean. Ohhh no! Good that the elves have a submarine ready to go! ![](https://i.giphy.com/media/8vIFoKU8s4m4CBqCao/giphy.webp) [Day one](https://adventofcode.com/2021/day/1) informs us that the sonar sweep has returned some results (our puzzle input) and now we need to find the count of increases in these measurements. I have chosen to use [Rust](https://www.rust-lang.org/) for this one. The code can be found [here](https://github.com/DiesDasJenes/advent_of_code/tree/master/2021/adc_d1). My approach to the first part of the puzzle was rather simple: - Read in the file as a vector of u32 - Iterate over the measurements and increase a counter when ever there is an increase - Profit Interestingly is that it was my first time using IntelliJ to create the Rust project, and it took me no time to get first results. I just wonder whether all unit tests are to be put into the production class itself, for now I am following what I see in the Rust workshops I have visited. Here is the method for part one of the puzzle. We expect a reference from a vector which contain unsigned numbers. I am still a beginner with this language so the decision whether to use i32 or u32 I made simply because all values in the puzzle input were positive. ```Rust fn count_increases_of_measurements(measurements: &Vec) -> u32 { let mut count_of_increases: u32 = 0; let mut latest_increased_measurement: &u32 = measurements.first().unwrap(); for measurement in measurements { if measurement > latest_increased_measurement { count_of_increases = count_of_increases.add(1) } latest_increased_measurement = measurement; } return count_of_increases; } ``` Now that solved part one of the puzzle only so that part two could give me a headache, but Rust came to the rescue. The new puzzle is to implement a sliding window over the vector so that we can calculate the sum of it's tuple. Let me visualise this: ```text 199 A 200 A B 208 A B C 210 B C D 200 E C D 207 E F D 240 E F G 269 F G H 260 G H 263 H ``` The puzzle is to calculate the sum of `199,200,208` and then switching to the next tuple `200,208,210` and so on. I never have seen this kind of problem, and so I was wondering for a short time how to solve this. In the end it's not really hard. You would create slices from the vector and save the sum of them to another vector. I was fiddling around with the vector as Rust showed me this great method `windows(n)`. It creates a list of tuples which I could just add up to get the sum. Voilà and so I had solved part two of day one. ```Rust fn collect_sum_of_triple_measurements(measurements: &Vec) -> Vec { let triples = measurements.windows(3); let mut collection_sums:Vec = Vec::new(); for triple in triples { let sum = triple.iter().sum(); collection_sums.push(sum); } return collection_sums } ``` ```Rust #[derive(Debug)] pub enum State { Start, Transient, Closed, } impl From<&'a str> for State { fn from(s: &'a str) -> Self { match s { "start" => State::Start, "closed" => State::Closed, _ => unreachable!(), } } } ``` That's it for day one so far. Write me in the comments how exited you are! --- ## Navigation - Parent: [Life, Tech & Adventures: A Journey in Bytes and Boardgames](https://blog.philippludewig.de/de/index.md) - Previous: [Advent of Code 2021 Day 2](https://blog.philippludewig.de/de/writing/advent-of-code-2021-day-2.md) - Next: [Let's take a break!](https://blog.philippludewig.de/de/writing/unpaid-leave-timeout.md)