Advent of Code

Complete 2024 to 2015 entries written in Rust for the annual Advent of Code challenge, solving 500 stars in less than 1 second.

Features

• Each solution uses the most efficient algorithms to the best of my knowledge.
• Self contained depending only on the std Rust library. No use of unsafe features.
• Consistently formatted with rustfmt and linted by clippy.
• Thoroughly commented with rustdoc generated documentation online.
• Test coverage with continuous integration provided by GitHub Actions.

Quickstart

Show details

Input

Place input files in input/yearYYYY/dayDD.txt including leading zeroes. For example:

• input/year2015/day23.txt
• input/year2023/day02.txt

Run

• Everything cargo run
• Specific year cargo run year2023
• Specific day cargo run year2023::day01
• Release profile (faster) cargo run --release
• Optimized for current CPU architecture (fastest) RUSTFLAGS="-C target-cpu=native" cargo run --release

Test

• Everything cargo test
• Specific year cargo test year2023
• Specific day cargo test year2023::day01
• Show STDOUT for debugging cargo test -- --nocapture

Benchmark

• Everything cargo bench
• Specific year cargo bench year2023
• Specific day cargo bench year2023::day01

Document

• Build docs including private items cargo doc --document-private-items
• Build doc then open HTML landing page cargo doc --document-private-items --open

Miscellaneous

• Code quality lints cargo clippy
• Consistent code formatting cargo fmt

Performance

Benchmarks are measured using the built-in cargo bench tool run on an Apple M2 Max. All 250 solutions from 2024 to 2015 complete sequentially in 585 milliseconds. Interestingly 84% of the total time is spent on just 9 solutions. Performance is reasonable even on older hardware, for example a 2011 MacBook Pro with an Intel i7-2720QM processor takes 3.5 seconds to run the same 225 solutions.

Year	Benchmark (ms)		Year	Benchmark (ms)
2015	24		2020	272
2016	120		2021	9
2017	89		2022	8
2018	35		2023	6
2019	16		2024	6

2024

Day	Problem	Solution	Benchmark (μs)
1	Historian Hysteria	Source	21
2	Red-Nosed Reports	Source	43
3	Mull It Over	Source	8
4	Ceres Search	Source	77
5	Print Queue	Source	18
6	Guard Gallivant	Source	386
7	Bridge Repair	Source	136
8	Resonant Collinearity	Source	8
9	Disk Fragmenter	Source	106
10	Hoof It	Source	38
11	Plutonian Pebbles	Source	248
12	Garden Groups	Source	289
13	Claw Contraption	Source	14
14	Restroom Redoubt	Source	74
15	Warehouse Woes	Source	303
16	Reindeer Maze	Source	390
17	Chronospatial Computer	Source	2
18	RAM Run	Source	42
19	Linen Layout	Source	118
20	Race Condition	Source	1354
21	Keypad Conundrum	Source	111
22	Monkey Market	Source	1350
23	LAN Party	Source	43
24	Crossed Wires	Source	36
25	Code Chronicle	Source	12

2023

Day	Problem	Solution	Benchmark (μs)
1	Trebuchet?!	Source	37
2	Cube Conundrum	Source	9
3	Gear Ratios	Source	53
4	Scratchcards	Source	20
5	If You Give A Seed A Fertilizer	Source	18
6	Wait For It	Source	1
7	Camel Cards	Source	71
8	Haunted Wasteland	Source	34
9	Mirage Maintenance	Source	18
10	Pipe Maze	Source	41
11	Cosmic Expansion	Source	12
12	Hot Springs	Source	440
13	Point of Incidence	Source	66
14	Parabolic Reflector Dish	Source	632
15	Lens Library	Source	84
16	The Floor Will Be Lava	Source	826
17	Clumsy Crucible	Source	2289
18	Lavaduct Lagoon	Source	17
19	Aplenty	Source	100
20	Pulse Propagation	Source	6
21	Step Counter	Source	182
22	Sand Slabs	Source	54
23	A Long Walk	Source	640
24	Never Tell Me The Odds	Source	95
25	Snowverload	Source	179

2022

Day	Problem	Solution	Benchmark (μs)
1	Calorie Counting	Source	14
2	Rock Paper Scissors	Source	3
3	Rucksack Reorganization	Source	13
4	Camp Cleanup	Source	8
5	Supply Stacks	Source	14
6	Tuning Trouble	Source	3
7	No Space Left On Device	Source	14
8	Treetop Tree House	Source	51
9	Rope Bridge	Source	107
10	Cathode-Ray Tube	Source	2
11	Monkey in the Middle	Source	1173
12	Hill Climbing Algorithm	Source	57
13	Distress Signal	Source	15
14	Regolith Reservoir	Source	205
15	Beacon Exclusion Zone	Source	2
16	Proboscidea Volcanium	Source	59
17	Pyroclastic Flow	Source	71
18	Boiling Boulders	Source	121
19	Not Enough Minerals	Source	74
20	Grove Positioning System	Source	3785
21	Monkey Math	Source	64
22	Monkey Map	Source	61
23	Unstable Diffusion	Source	1521
24	Blizzard Basin	Source	62
25	Full of Hot Air	Source	3

2021

Day	Problem	Solution	Benchmark (μs)
1	Sonar Sweep	Source	6
2	Dive!	Source	12
3	Binary Diagnostic	Source	20
4	Giant Squid	Source	12
5	Hydrothermal Venture	Source	181
6	Lanternfish	Source	1
7	The Treachery of Whales	Source	8
8	Seven Segment Search	Source	14
9	Smoke Basin	Source	64
10	Syntax Scoring	Source	25
11	Dumbo Octopus	Source	55
12	Passage Pathing	Source	25
13	Transparent Origami	Source	22
14	Extended Polymerization	Source	11
15	Chiton	Source	2403
16	Packet Decoder	Source	6
17	Trick Shot	Source	7
18	Snailfish	Source	501
19	Beacon Scanner	Source	615
20	Trench Map	Source	2066
21	Dirac Dice	Source	278
22	Reactor Reboot	Source	378
23	Amphipod	Source	1714
24	Arithmetic Logic Unit	Source	4
25	Sea Cucumber	Source	551

2020

Day	Problem	Solution	Benchmark (μs)
1	Report Repair	Source	12
2	Password Philosophy	Source	35
3	Toboggan Trajectory	Source	12
4	Passport Processing	Source	49
5	Binary Boarding	Source	11
6	Custom Customs	Source	35
7	Handy Haversacks	Source	69
8	Handheld Halting	Source	8
9	Encoding Error	Source	9
10	Adapter Array	Source	1
11	Seating System	Source	4537
12	Rain Risk	Source	12
13	Shuttle Search	Source	1
14	Docking Data	Source	83
15	Rambunctious Recitation	Source	147000
16	Ticket Translation	Source	120
17	Conway Cubes	Source	443
18	Operation Order	Source	24
19	Monster Messages	Source	362
20	Jurassic Jigsaw	Source	42
21	Allergen Assessment	Source	45
22	Crab Combat	Source	5911
23	Crab Cups	Source	110000
24	Lobby Layout	Source	4320
25	Combo Breaker	Source	20

2019

Day	Problem	Solution	Benchmark (μs)
1	The Tyranny of the Rocket Equation	Source	1
2	1202 Program Alarm	Source	1
3	Crossed Wires	Source	17
4	Secure Container	Source	12
5	Sunny with a Chance of Asteroids	Source	3
6	Universal Orbit Map	Source	29
7	Amplification Circuit	Source	79
8	Space Image Format	Source	4
9	Sensor Boost	Source	1008
10	Monitoring Station	Source	1092
11	Space Police	Source	341
12	The N-Body Problem	Source	1309
13	Care Package	Source	2510
14	Space Stoichiometry	Source	17
15	Oxygen System	Source	360
16	Flawed Frequency Transmission	Source	1956
17	Set and Forget	Source	338
18	Many-Worlds Interpretation	Source	1157
19	Tractor Beam	Source	688
20	Donut Maze	Source	189
21	Springdroid Adventure	Source	1785
22	Slam Shuffle	Source	12
23	Category Six	Source	670
24	Planet of Discord	Source	232
25	Cryostasis	Source	2047

2018

Day	Problem	Solution	Benchmark (μs)
1	Chronal Calibration	Source	16
2	Inventory Management System	Source	78
3	No Matter How You Slice It	Source	55
4	Repose Record	Source	46
5	Alchemical Reduction	Source	390
6	Chronal Coordinates	Source	41
7	The Sum of Its Parts	Source	8
8	Memory Maneuver	Source	24
9	Marble Mania	Source	909
10	The Stars Align	Source	11
11	Chronal Charge	Source	1404
12	Subterranean Sustainability	Source	77
13	Mine Cart Madness	Source	382
14	Chocolate Charts	Source	24000
15	Beverage Bandits	Source	583
16	Chronal Classification	Source	37
17	Reservoir Research	Source	151
18	Settlers of The North Pole	Source	384
19	Go With The Flow	Source	1
20	A Regular Map	Source	36
21	Chronal Conversion	Source	66
22	Mode Maze	Source	3396
23	Experimental Emergency Teleportation	Source	506
24	Immune System Simulator 20XX	Source	2056
25	Four-Dimensional Adventure	Source	323

2017

Day	Problem	Solution	Benchmark (μs)
1	Inverse Captcha	Source	1
2	Corruption Checksum	Source	2
3	Spiral Memory	Source	2
4	High-Entropy Passphrases	Source	98
5	A Maze of Twisty Trampolines, All Alike	Source	22000
6	Memory Reallocation	Source	81
7	Recursive Circus	Source	93
8	I Heard You Like Registers	Source	47
9	Stream Processing	Source	23
10	Knot Hash	Source	66
11	Hex Ed	Source	18
12	Digital Plumber	Source	61
13	Packet Scanners	Source	1
14	Disk Defragmentation	Source	438
15	Dueling Generators	Source	26000
16	Permutation Promenade	Source	68
17	Spinlock	Source	85
18	Duet	Source	7
19	A Series of Tubes	Source	19
20	Particle Swarm	Source	245
21	Fractal Art	Source	5
22	Sporifica Virus	Source	36000
23	Coprocessor Conflagration	Source	55
24	Electromagnetic Moat	Source	275
25	The Halting Problem	Source	3698

2016

Day	Problem	Solution	Benchmark (μs)
1	No Time for a Taxicab	Source	3
2	Bathroom Security	Source	29
3	Squares With Three Sides	Source	24
4	Security Through Obscurity	Source	79
5	How About a Nice Game of Chess?	Source	37000
6	Signals and Noise	Source	4
7	Internet Protocol Version 7	Source	364
8	Two-Factor Authentication	Source	9
9	Explosives in Cyberspace	Source	6
10	Balance Bots	Source	16
11	Radioisotope Thermoelectric Generators	Source	719
12	Leonardo's Monorail	Source	1
13	A Maze of Twisty Little Cubicles	Source	3
14	One-Time Pad	Source	77000
15	Timing is Everything	Source	1
16	Dragon Checksum	Source	1
17	Two Steps Forward	Source	3858
18	Like a Rogue	Source	728
19	An Elephant Named Joseph	Source	1
20	Firewall Rules	Source	21
21	Scrambled Letters and Hash	Source	10
22	Grid Computing	Source	28
23	Safe Cracking	Source	1
24	Air Duct Spelunking	Source	337
25	Clock Signal	Source	1

2015

Day	Problem	Solution	Benchmark (μs)
1	Not Quite Lisp	Source	2
2	I Was Told There Would Be No Math	Source	8
3	Perfectly Spherical Houses in a Vacuum	Source	95
4	The Ideal Stocking Stuffer	Source	14000
5	Doesn't He Have Intern-Elves For This?	Source	38
6	Probably a Fire Hazard	Source	6572
7	Some Assembly Required	Source	27
8	Matchsticks	Source	12
9	All in a Single Night	Source	34
10	Elves Look, Elves Say	Source	15
11	Corporate Policy	Source	1
12	JSAbacusFramework.io	Source	83
13	Knights of the Dinner Table	Source	37
14	Reindeer Olympics	Source	28
15	Science for Hungry People	Source	53
16	Aunt Sue	Source	20
17	No Such Thing as Too Much	Source	45
18	Like a GIF For Your Yard	Source	154
19	Medicine for Rudolph	Source	187
20	Infinite Elves and Infinite Houses	Source	1667
21	RPG Simulator 20XX	Source	2
22	Wizard Simulator 20XX	Source	235
23	Opening the Turing Lock	Source	6
24	It Hangs in the Balance	Source	380
25	Let It Snow	Source	1