timsearle / aoc-2021

AoC-2021

Advent Of Code (AoC) 2021

This are my solutions to the Advent Of Code 2021 event. This year I've been playing along with timsearle and SFrost007, please check out their solutions if you're interested.

Project approach

This swift package manager project contains my MacOS command line tool, a framework with all of the logic to solve the puzzles and a test framework to validate against the AoC examples that are given in the puzzle descriptions.

The idea is to use the example problems/solutions provided in the puzzles to do TDD, but sometimes there are no examples that allow TDD.

There's a config.swift file hidden using git-secret. This is the format of the file:

import Foundation

enum Config {
    static let year = 2021
    // This is the session cookie from your browser after logging in to https://adventofcode.com/
    static let session = "[TOKEN]"
}

Running

To run day 1:

• Either create a file called day1.txt with your puzzle input, or add your AoC session cookie to the code and it'll be created automatically
• Then run swift run AoC 1 in Terminal

Implementation notes

Day 1

Logged on to find SFrost007 had already got his 2 stars! Although this year we're not competing on it (I cheated by having childcare duties meaning I could work on it before everyone else woke up) :D

First part was an array look-ahead problem, so just did a loop making sure I didn't go out of bounds and keeping a seperate variable for what I was looking at. Second part needed a window calculating, so made and tested a function for that. I really struggled with the indexes of the array bounds checking, so it took me 10 mins to write a function that should have taken 2. Thank goodness for tests otherwise that could have been an hour. I'm rusty from last year.

Edit: I went back and added the swift-algorithms package and made a funciton to compute the answer, part 1 just used it with the array, and part 2 with the windows calculated using the Algorithms library.

Day 2

Pretty simple algorithm for today, just split the lines using a space, then added first part and the second part converted to an Int to a tuple for looping over and added the algorithm as simple if statements for both parts.