Advent of Code

Complete 2022 to 2015 entries for the annual Advent of Code challenge, written in concise idiomatic functional Scala.

Features

As far as possible, each day's solution embraces the following approaches:

• Self-contained within a single file, depending only on the standard Scala library.
• Immutable data structures, using copy-on-write to update.
• Pure functions with side effects, such as printing to the screen, restricted to a single main method.

The minimal SBT project provides:

• Straightforward consistent layout of code, resources and tests.
• Unit test coverage based on the sample input.
• Continuous integration using GitHub Actions.

Years

• 2022
• 2021
• 2020
• 2019
• 2018
• 2017
• 2016
• 2015

2022

Day	Problem	Solution
1	Calorie Counting	Source
2	Rock Paper Scissors	Source
3	Rucksack Reorganization	Source
4	Camp Cleanup	Source
5	Supply Stacks	Source
6	Tuning Trouble	Source
7	No Space Left On Device	Source
8	Treetop Tree House	Source
9	Rope Bridge	Source
10	Cathode-Ray Tube	Source
11	Monkey in the Middle	Source
12	Hill Climbing Algorithm	Source
13	Distress Signal	Source
14	Regolith Reservoir	Source
15	Beacon Exclusion Zone	Source
16	Proboscidea Volcanium	Source
17	Pyroclastic Flow	Source
18	Boiling Boulders	Source
19	Not Enough Minerals	Source
20	Grove Positioning System	Source
21	Monkey Math	Source
22	Monkey Map	Source
23	Unstable Diffusion	Source
24	Blizzard Basin	Source
25	Full of Hot Air	Source

2021

Day	Problem	Solution
1	Sonar Sweep	Source
2	Dive!	Source
3	Binary Diagnostic	Source
4	Giant Squid	Source
5	Hydrothermal Venture	Source
6	Lanternfish	Source
7	The Treachery of Whales	Source
8	Seven Segment Search	Source
9	Smoke Basin	Source
10	Syntax Scoring	Source
11	Dumbo Octopus	Source
12	Passage Pathing	Source
13	Transparent Origami	Source
14	Extended Polymerization	Source
15	Chiton	Source
16	Packet Decoder	Source
17	Trick Shot	Source
18	Snailfish	Source
19	Beacon Scanner	Source
20	Trench Map	Source
21	Dirac Dice	Source
22	Reactor Reboot	Source
23	Amphipod	Source
24	Arithmetic Logic Unit	Source
25	Sea Cucumber	Source

2020

Day	Problem	Solution
1	Report Repair	Source
2	Password Philosophy	Source
3	Toboggan Trajectory	Source
4	Passport Processing	Source
5	Binary Boarding	Source
6	Custom Customs	Source
7	Handy Haversacks	Source
8	Handheld Halting	Source
9	Encoding Error	Source
10	Adapter Array	Source
11	Seating System	Source
12	Rain Risk	Source
13	Shuttle Search	Source
14	Docking Data	Source
15	Rambunctious Recitation	Source
16	Ticket Translation	Source
17	Conway Cubes	Source
18	Operation Order	Source
19	Monster Messages	Source
20	Jurassic Jigsaw	Source
21	Allergen Assessment	Source
22	Crab Combat	Source
23	Crab Cups	Source
24	Lobby Layout	Source
25	Combo Breaker	Source

2019

Day	Problem	Solution
1	The Tyranny of the Rocket Equation	Source
2	1202 Program Alarm	Source
3	Crossed Wires	Source
4	Secure Container	Source
5	Sunny with a Chance of Asteroids	Source
6	Universal Orbit Map	Source
7	Amplification Circuit	Source
8	Space Image Format	Source
9	Sensor Boost	Source
10	Monitoring Station	Source
11	Space Police	Source
12	The N-Body Problem	Source
13	Care Package	Source
14	Space Stoichiometry	Source
15	Oxygen System	Source
16	Flawed Frequency Transmission	Source
17	Set and Forget	Source
18	Many-Worlds Interpretation	Source
19	Tractor Beam	Source
20	Donut Maze	Source
21	Springdroid Adventure	Source
22	Slam Shuffle	Source
23	Category Six	Source
24	Planet of Discord	Source
25	Cryostasis	Source

2018

Day	Problem	Solution
1	Chronal Calibration	Source
2	Inventory Management System	Source
3	No Matter How You Slice It	Source
4	Repose Record	Source
5	Alchemical Reduction	Source
6	Chronal Coordinates	Source
7	The Sum of Its Parts	Source
8	Memory Maneuver	Source
9	Marble Mania	Source
10	The Stars Align	Source
11	Chronal Charge	Source
12	Subterranean Sustainability	Source
13	Mine Cart Madness	Source
14	Chocolate Charts	Source
15	Beverage Bandits	Source
16	Chronal Classification	Source
17	Reservoir Research	Source
18	Settlers of The North Pole	Source
19	Go With The Flow	Source
20	A Regular Map	Source
21	Chronal Conversion	Source
22	Mode Maze	Source
23	Experimental Emergency Teleportation	Source
24	Immune System Simulator 20XX	Source
25	Four-Dimensional Adventure	Source

2017

Day	Problem	Solution
1	Inverse Captcha	Source
2	Corruption Checksum	Source
3	Spiral Memory	Source
4	High-Entropy Passphrases	Source
5	A Maze of Twisty Trampolines, All Alike	Source
6	Memory Reallocation	Source
7	Recursive Circus	Source
8	I Heard You Like Registers	Source
9	Stream Processing	Source
10	Knot Hash	Source
11	Hex Ed	Source
12	Digital Plumber	Source
13	Packet Scanners	Source
14	Disk Defragmentation	Source
15	Dueling Generators	Source
16	Permutation Promenade	Source
17	Spinlock	Source
18	Duet	Source
19	A Series of Tubes	Source
20	Particle Swarm	Source
21	Fractal Art	Source
22	Sporifica Virus	Source
23	Coprocessor Conflagration	Source
24	Electromagnetic Moat	Source
25	The Halting Problem	Source

2016

Day	Problem	Solution
1	No Time for a Taxicab	Source
2	Bathroom Security	Source
3	Squares With Three Sides	Source
4	Security Through Obscurity	Source
5	How About a Nice Game of Chess?	Source
6	Signals and Noise	Source
7	Internet Protocol Version 7	Source
8	Two-Factor Authentication	Source
9	Explosives in Cyberspace	Source
10	Balance Bots	Source
11	Radioisotope Thermoelectric Generators	Source
12	Leonardo's Monorail	Source
13	A Maze of Twisty Little Cubicles	Source
14	One-Time Pad	Source
15	Timing is Everything	Source
16	Dragon Checksum	Source
17	Two Steps Forward	Source
18	Like a Rogue	Source
19	An Elephant Named Joseph	Source
20	Firewall Rules	Source
21	Scrambled Letters and Hash	Source
22	Grid Computing	Source
23	Safe Cracking	Source
24	Air Duct Spelunking	Source
25	Clock Signal	Source

2015

Day	Problem	Solution
1	Not Quite Lisp	Source
2	I Was Told There Would Be No Math	Source
3	Perfectly Spherical Houses in a Vacuum	Source
4	The Ideal Stocking Stuffer	Source
5	Doesn't He Have Intern-Elves For This?	Source
6	Probably a Fire Hazard	Source
7	Some Assembly Required	Source
8	Matchsticks	Source
9	All in a Single Night	Source
10	Elves Look, Elves Say	Source
11	Corporate Policy	Source
12	JSAbacusFramework.io	Source
13	Knights of the Dinner Table	Source
14	Reindeer Olympics	Source
15	Science for Hungry People	Source
16	Aunt Sue	Source
17	No Such Thing as Too Much	Source
18	Like a GIF For Your Yard	Source
19	Medicine for Rudolph	Source
20	Infinite Elves and Infinite Houses	Source
21	RPG Simulator 20XX	Source
22	Wizard Simulator 20XX	Source
23	Opening the Turing Lock	Source
24	It Hangs in the Balance	Source
25	Let It Snow	Source