Advent of Code [![checks-badge]][checks-link] [![docs-badge]][docs-link]

Blazing fast Rust solutions for every Advent of Code puzzle from 2015 to 2025, taking 467 milliseconds to solve all 524 stars. Each solution is carefully optimized for performance while ensuring the code remains concise, readable, and idiomatic.

Features

• Minimal - Depends only on the standard library.
• High Quality - Formatted with rustfmt, linted by clippy and continuously tested via GitHub Actions. No unsafe code.
• Well Documented - Every solution is comprehensively commented with rustdoc-generated documentation also available online.

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
• Enable SIMD feature cargo run --features simd
• 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

Linting and Formatting

• Clippy lints cargo clippy --all-targets --all-features
• Consistent code formatting cargo fmt -- `find . -name "*.rs"`

Document

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

Contributing

Improvements to solutions are always appreciated. Please see the detailed instructions on how to get started.

Performance

Benchmarks are measured using the built-in cargo bench tool run on an Apple M2 Max. Interestingly, 86% 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 262 solutions.

Year	2025
Benchmark (ms)	2

Year	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
Benchmark (ms)	5	5	5	8	220	13	33	56	107	13

2025

Day	Problem	Solution	Benchmark (μs)
1	Secret Entrance	Source	24
2	Gift Shop	Source	1
3	Lobby	Source	21
4	Printing Department	Source	177
5	Cafeteria	Source	20
6	Trash Compactor	Source	20
7	Laboratories	Source	5
8	Playground	Source	441
9	Movie Theater	Source	40
10	Factory	Source	194
11	Reactor	Source	59
12	Christmas Tree Farm	Source	25

2024

Day	Problem	Solution	Benchmark (μs)
1	Historian Hysteria	Source	21
2	Red-Nosed Reports	Source	40
3	Mull It Over	Source	8
4	Ceres Search	Source	74
5	Print Queue	Source	18
6	Guard Gallivant	Source	405
7	Bridge Repair	Source	136
8	Resonant Collinearity	Source	8
9	Disk Fragmenter	Source	106
10	Hoof It	Source	38
11	Plutonian Pebbles	Source	227
12	Garden Groups	Source	289
13	Claw Contraption	Source	14
14	Restroom Redoubt	Source	74
15	Warehouse Woes	Source	303
16	Reindeer Maze	Source	350
17	Chronospatial Computer	Source	2
18	RAM Run	Source	42
19	Linen Layout	Source	110
20	Race Condition	Source	1113
21	Keypad Conundrum	Source	19
22	Monkey Market	Source	688
23	LAN Party	Source	43
24	Crossed Wires	Source	23
25	Code Chronicle	Source	8

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	35
11	Cosmic Expansion	Source	12
12	Hot Springs	Source	455
13	Point of Incidence	Source	66
14	Parabolic Reflector Dish	Source	632
15	Lens Library	Source	84
16	The Floor Will Be Lava	Source	160
17	Clumsy Crucible	Source	2379
18	Lavaduct Lagoon	Source	11
19	Aplenty	Source	100
20	Pulse Propagation	Source	6
21	Step Counter	Source	182
22	Sand Slabs	Source	40
23	A Long Walk	Source	68
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	13
6	Tuning Trouble	Source	3
7	No Space Left On Device	Source	10
8	Treetop Tree House	Source	51
9	Rope Bridge	Source	99
10	Cathode-Ray Tube	Source	2
11	Monkey in the Middle	Source	244
12	Hill Climbing Algorithm	Source	57
13	Distress Signal	Source	15
14	Regolith Reservoir	Source	146
15	Beacon Exclusion Zone	Source	2
16	Proboscidea Volcanium	Source	59
17	Pyroclastic Flow	Source	71
18	Boiling Boulders	Source	52
19	Not Enough Minerals	Source	74
20	Grove Positioning System	Source	2685
21	Monkey Math	Source	64
22	Monkey Map	Source	61
23	Unstable Diffusion	Source	1061
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	1
3	Binary Diagnostic	Source	8
4	Giant Squid	Source	8
5	Hydrothermal Venture	Source	136
6	Lanternfish	Source	1
7	The Treachery of Whales	Source	4
8	Seven Segment Search	Source	14
9	Smoke Basin	Source	33
10	Syntax Scoring	Source	14
11	Dumbo Octopus	Source	55
12	Passage Pathing	Source	25
13	Transparent Origami	Source	12
14	Extended Polymerization	Source	11
15	Chiton	Source	2290
16	Packet Decoder	Source	6
17	Trick Shot	Source	3
18	Snailfish	Source	440
19	Beacon Scanner	Source	378
20	Trench Map	Source	511
21	Dirac Dice	Source	337
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	1
2	Password Philosophy	Source	35
3	Toboggan Trajectory	Source	8
4	Passport Processing	Source	33
5	Binary Boarding	Source	11
6	Custom Customs	Source	8
7	Handy Haversacks	Source	58
8	Handheld Halting	Source	7
9	Encoding Error	Source	9
10	Adapter Array	Source	1
11	Seating System	Source	831
12	Rain Risk	Source	4
13	Shuttle Search	Source	1
14	Docking Data	Source	83
15	Rambunctious Recitation	Source	103000
16	Ticket Translation	Source	104
17	Conway Cubes	Source	102
18	Operation Order	Source	24
19	Monster Messages	Source	462
20	Jurassic Jigsaw	Source	42
21	Allergen Assessment	Source	45
22	Crab Combat	Source	5333
23	Crab Cups	Source	109000
24	Lobby Layout	Source	330
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	7
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	342
11	Space Police	Source	320
12	The N-Body Problem	Source	838
13	Care Package	Source	2527
14	Space Stoichiometry	Source	17
15	Oxygen System	Source	291
16	Flawed Frequency Transmission	Source	224
17	Set and Forget	Source	215
18	Many-Worlds Interpretation	Source	1039
19	Tractor Beam	Source	216
20	Donut Maze	Source	189
21	Springdroid Adventure	Source	1360
22	Slam Shuffle	Source	12
23	Category Six	Source	670
24	Planet of Discord	Source	232
25	Cryostasis	Source	1196

2018

Day	Problem	Solution	Benchmark (μs)
1	Chronal Calibration	Source	11
2	Inventory Management System	Source	48
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	2
8	Memory Maneuver	Source	23
9	Marble Mania	Source	909
10	The Stars Align	Source	11
11	Chronal Charge	Source	542
12	Subterranean Sustainability	Source	22
13	Mine Cart Madness	Source	349
14	Chocolate Charts	Source	24000
15	Beverage Bandits	Source	563
16	Chronal Classification	Source	37
17	Reservoir Research	Source	118
18	Settlers of The North Pole	Source	384
19	Go With The Flow	Source	1
20	A Regular Map	Source	24
21	Chronal Conversion	Source	66
22	Mode Maze	Source	1994
23	Experimental Emergency Teleportation	Source	44
24	Immune System Simulator 20XX	Source	1943
25	Four-Dimensional Adventure	Source	97

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	86
5	A Maze of Twisty Trampolines, All Alike	Source	18000
6	Memory Reallocation	Source	79
7	Recursive Circus	Source	93
8	I Heard You Like Registers	Source	35
9	Stream Processing	Source	23
10	Knot Hash	Source	66
11	Hex Ed	Source	13
12	Digital Plumber	Source	59
13	Packet Scanners	Source	1
14	Disk Defragmentation	Source	488
15	Dueling Generators	Source	20000
16	Permutation Promenade	Source	68
17	Spinlock	Source	23
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	16000
23	Coprocessor Conflagration	Source	11
24	Electromagnetic Moat	Source	275
25	The Halting Problem	Source	1672

2016

Day	Problem	Solution	Benchmark (μs)
1	No Time for a Taxicab	Source	2
2	Bathroom Security	Source	9
3	Squares With Three Sides	Source	26
4	Security Through Obscurity	Source	67
5	How About a Nice Game of Chess?	Source	33000
6	Signals and Noise	Source	3
7	Internet Protocol Version 7	Source	364
8	Two-Factor Authentication	Source	9
9	Explosives in Cyberspace	Source	7
10	Balance Bots	Source	14
11	Radioisotope Thermoelectric Generators	Source	2
12	Leonardo's Monorail	Source	1
13	A Maze of Twisty Little Cubicles	Source	2
14	One-Time Pad	Source	71000
15	Timing is Everything	Source	1
16	Dragon Checksum	Source	1
17	Two Steps Forward	Source	3606
18	Like a Rogue	Source	400
19	An Elephant Named Joseph	Source	1
20	Firewall Rules	Source	21
21	Scrambled Letters and Hash	Source	10
22	Grid Computing	Source	20
23	Safe Cracking	Source	1
24	Air Duct Spelunking	Source	117
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	6
3	Perfectly Spherical Houses in a Vacuum	Source	95
4	The Ideal Stocking Stuffer	Source	12000
5	Doesn't He Have Intern-Elves For This?	Source	38
6	Probably a Fire Hazard	Source	454
7	Some Assembly Required	Source	8
8	Matchsticks	Source	5
9	All in a Single Night	Source	7
10	Elves Look, Elves Say	Source	17
11	Corporate Policy	Source	1
12	JSAbacusFramework.io	Source	71
13	Knights of the Dinner Table	Source	10
14	Reindeer Olympics	Source	21
15	Science for Hungry People	Source	43
16	Aunt Sue	Source	20
17	No Such Thing as Too Much	Source	4
18	Like a GIF For Your Yard	Source	47
19	Medicine for Rudolph	Source	23
20	Infinite Elves and Infinite Houses	Source	1
21	RPG Simulator 20XX	Source	2
22	Wizard Simulator 20XX	Source	150
23	Opening the Turing Lock	Source	6
24	It Hangs in the Balance	Source	23
25	Let It Snow	Source	1