My attempts at the Advent of Code 2023 challenges in PHP.

Solutions

Day	Name	Code	Time †
01	Trebuchet?!	src/Day01.php	0.002655s
02	Cube Conundrum	src/Day02.php	0.001402s
03	Gear Ratios	src/Day03.php	0.006805s
04	Scratchcards	src/Day04.php	0.006466s
05	If You Give A Seed A Fertilizer	src/Day05.php	0.002637s
06	Wait For It	src/Day06.php	0.000059s
07	Camel Cards	src/Day07.php	0.239075s
08	Haunted Wasteland	src/Day08.php	0.066197s
09	Mirage Maintenance	src/Day09.php	0.027672s
10	Pipe Maze	src/Day10.php	0.023185s
11	Cosmic Expansion	src/Day11.php	1.122419s
12	Hot Springs	src/Day12.php	Part 2 Unsolved
13	Point of Incidence	src/Day13.php	0.015861s
14	Parabolic Reflector Dish	src/Day14.php	0.996860s
15	Lens Library		Not Started
16	The Floor Will Be Lava	src/Day16.php	5.479180s

† The measured execution time in GitHub Actions

Installation

Installing on your machine

Installation with vary on each system. For a full environment the following dependencies should be installed:

• PHP 8.3
• Composer 2.6
• Xdebug 3.3

Installing with Docker

Using Docker avoids the complexity of installing the dependencies listed above.

Once Docker is installed, a Docker image can be built by running:

make docker-build

Once built, an interactive shell with the project directory mounted can be started by running:

make shell

How to run

Before running the code, the PHP dependencies must be installed by running:

composer install

All puzzles can be executed by running:

php src/main.php

Individual puzzles can be executed by adding the day-number:

php src/main.php 01

The solutions can be benchmarked by adding the flag -b:

php src/main.php 01 -b

Why is the input data encrypted?

Note that the input data included in this repository have been encrypted, and exist purely for personal use. This is because the input data is the sole property of Advent of Code, and is not licensed for reproduction or distribution. To test with your own input, replace the contents of the file src/Day**.data with your own inputs from adventofcode.com.

If you somehow are in possession of the encryption key, you can unlock it using git-crypt by running:

echo "${BASE64_ENCODED_KEY}" | base64 -d | git-crypt unlock -

How to develop

As mentioned above, the code for each puzzle can be run individually. But this project has additional tools to help with development.

Tests

Test-driven-development using unit tests can help with solving a puzzle by ensuring individual functions work as expected. Tests can be added in tests/Unit/* and run using PHPUnit. The flags --testdox and --colors can help make the output more legible:

vendor/bin/phpunit tests/Unit/Day01Test.php --testdox --colors

This can be run quickly for all tests from the Makefile:

make tests

Note that some of the test data includes sample data from adventofcode.com, which have been encrypted for the same legal reasons mentioned above in "Why is the input data encrypted?". These tests will be skipped when attempting to run the tests.

Linting & Static Analysis

Following code standards can help make the code more legible and running static analysis tools can spot issues in the code. This project comes with PHP CodeSniffer and Psalm:

vendor/bin/phpcs -p --standard=PSR12 src/ tests/
vendor/bin/psalm --show-info=true

These can be run quickly from the Makefile:

make lint

Attribution

• Hero background image by Eugene Golovesov on Unsplash.