difficulty.md

🎯 Solutions by Difficulty

← Home

🟢 XS

Year	Day	Title	Tags	Source
2015	1	Not Quite Lisp	sequence	day_01.ex
2015	2	I Was Told There Would Be No Math	geometry	day_02.ex
2015	3	Perfectly Spherical Houses in a Vacuum	grid, set	day_03.ex
2015	5	Doesn't He Have Intern-Elves For This?	string	day_05.ex
2015	10	Elves Look, Elves Say	reduction, sequence, string-encoding	day_10.ex
2015	11	Corporate Policy	sequence, validation	day_11.ex
2015	12	JSAbacusFramework.io	json	day_12.ex
2016	2	Bathroom Security	grid	day_02.ex
2016	3	Squares With Three Sides	count, geometry, matrix	day_03.ex
2016	4	Security Through Obscurity	checksum, sequence	day_04.ex
2016	6	Signals and Noise	optimization, sequence	day_06.ex
2016	7	Internet Protocol Version 7	count, validation	day_07.ex
2017	1	Inverse Captcha	sliding-window	day_01.ex
2017	2	Corruption Checksum	math, sequence	day_02.ex
2017	4	High-Entropy Passphrases	validation	day_04.ex
2019	1	The Tyranny of the Rocket Equation	math	day_01.ex
2019	2	1202 Program Alarm	int-code, op-code	day_02.ex
2019	3	Crossed Wires	grid, set	day_03.ex
2019	4	Secure Container	inline-input, sequence	day_04.ex
2019	5	Sunny with a Chance of Asteroids	int-code, op-code	day_05.ex
2019	6	Universal Orbit Map	graph, routing	day_06.ex
2019	8	Space Image Format	sequence, visual-result	day_08.ex
2020	1	Report Repair	math, set	day_01.ex
2020	2	Password Philosophy	parsing, string	day_02.ex
2020	3	Toboggan Trajectory	grid, walk	day_03.ex
2020	5	Binary Boarding	binary-space, partitioning, walk	day_05.ex
2020	6	Custom Customs	count, set	day_06.ex
2021	1	Sonar Sweep	sequence, sliding-window	day_01.ex
2021	2	Dive!	grid	day_02.ex
2021	5	Hydrothermal Venture	set	day_05.ex
2021	7	The Treachery of Whales	calculation	day_07.ex
2022	1	Calorie Counting	sequence	day_01.ex
2022	2	Rock Paper Scissors	table-lookup	day_02.ex
2022	3	Rucksack Reorganization	set	day_03.ex
2022	4	Camp Cleanup	ranges, set	day_04.ex
2022	6	Tuning Trouble	bitwise, set	day_06.ex
2022	7	No Space Left On Device	op-code, sequence	day_07.ex
2023	1	Trebuchet?!	parsing	day_01.ex
2023	4	Scratchcards	reduction, set	day_04.ex
2023	6	Wait For It	math	day_06.ex
2023	9	Mirage Maintenance	reduction, sequence	day_09.ex
2024	1	Historian Hysteria	sequence	day_01.ex
2024	3	Mull It Over	fsm, parsing	day_03.ex
2024	5	Print Queue	graph, sort, topological-sort	day_05.ex

🟡 S

Year	Day	Title	Tags	Source
2015	4	The Ideal Stocking Stuffer	annoying, md5	day_04.ex
2015	9	All in a Single Night	graph, routing	day_09.ex
2015	13	Knights of the Dinner Table	dynamic-programming, graph	day_13.ex
2015	14	Reindeer Olympics	measurement, recursion, sequence	day_14.ex
2015	17	No Such Thing as Too Much	combinatorics	day_17.ex
2016	1	No Time for a Taxicab	grid, measurement, set	day_01.ex
2016	5	How About a Nice Game of Chess?	binary, md5, slow	day_05.ex
2016	12	Leonardo's Monorail	assembunny, optimization	day_12.ex
2017	5	A Maze of Twisty Trampolines, All Alike	atomics, random-access	day_05.ex
2017	8	I Heard You Like Registers	op-code	day_08.ex
2017	9	Stream Processing	fsm	day_09.ex
2017	10	Knot Hash	hash	day_10.ex
2017	12	Digital Plumber	connectivity, graph	day_12.ex
2017	13	Packet Scanners	optimization, sequence	day_13.ex
2018	1	Chronal Calibration	sequence, set	day_01.ex
2018	2	Inventory Management System	checksum, set, string-result	day_02.ex
2018	4	Repose Record	date-time, map, sequence, sort	day_04.ex
2018	6	Chronal Coordinates	geometry, grid, optimization, parallel	day_06.ex
2018	9	Marble Mania	sequence, slow, zipper	day_09.ex
2020	4	Passport Processing	parsing, validation	day_04.ex
2020	7	Handy Haversacks	graph, recursion	day_07.ex
2020	8	Handheld Halting	emulation, recursion	day_08.ex
2020	9	Encoding Error	set, sliding-window	day_09.ex
2020	10	Adapter Array	dynamic-programming, sort	day_10.ex
2020	12	Rain Risk	geometry, rotation, walk	day_12.ex
2020	25	Combo Breaker	math	day_25.ex
2021	3	Binary Diagnostic	calculation	day_03.ex
2021	4	Giant Squid	grid, optimization, random-access	day_04.ex
2021	6	Lanternfish	map	day_06.ex
2022	5	Supply Stacks	parsing, sequence, stack	day_05.ex
2022	13	Distress Signal	json, sequence	day_13.ex
2022	21	Monkey Math	large-number, math, op-code	day_21.ex
2023	2	Cube Conundrum	reduction	day_02.ex
2023	8	Haunted Wasteland	math, sequence	day_08.ex
2023	11	Cosmic Expansion	grid, measurement	day_11.ex
2023	15	Lens Library	hash, sequence	day_15.ex
2024	2	Red-Nosed Reports	sequence, validation	day_02.ex
2024	4	Ceres Search	grid	day_04.ex
2024	7	Bridge Repair	enumeration, recursion	day_07.ex
2024	8	Resonant Collinearity	enumeration, geometry, grid	day_08.ex
2025	1	Secret Entrance	safe-dial, simulation	day_01.ex
2025	5	Cafeteria	interval-merging, ranges, simulation	day_05.ex
2025	8	Playground	union-find	day_08.ex

🟠 M

Year	Day	Title	Tags	Source
2015	6	Probably a Fire Hazard	grid, reduction, vector	day_06.ex
2015	7	Some Assembly Required	bitwise, graph, logic-gates	day_07.ex
2015	8	Matchsticks	annoying, string-encoding	day_08.ex
2015	15	Science for Hungry People	quadratic-time, sequence	day_15.ex
2015	16	Aunt Sue	annoying, count	day_16.ex
2015	18	Like a GIF For Your Yard	grid, map, simulation	day_18.ex
2015	19	Medicine for Rudolph	random-access, vector	day_19.ex
2015	22	Wizard Simulator 20XX	dijkstra, simulation	day_22.ex
2015	23	Opening the Turing Lock	emulation, op-code	day_23.ex
2015	25	Let It Snow	math, table-lookup	day_25.ex
2016	8	Two-Factor Authentication	matrix, op-code, visual-result	day_08.ex
2016	9	Explosives in Cyberspace	sequence, unfold	day_09.ex
2016	10	Balance Bots	dataflow, graph, simulation	day_10.ex
2016	13	A Maze of Twisty Little Cubicles	a-star, graph, implicit-graph	day_13.ex
2016	17	Two Steps Forward	bfs, graph, md5, state-space-search	day_17.ex
2016	24	Air Duct Spelunking	graph, grid, matrix, pathfinding, tsp	day_24.ex
2016	25	Clock Signal	assembunny, optimization, simulation	day_25.ex
2017	3	Spiral Memory	matrix, spiral	day_03.ex
2017	6	Memory Reallocation	reduction, sequence	day_06.ex
2017	7	Recursive Circus	graph, tree	day_07.ex
2017	14	Disk Defragmentation	graph, hash	day_14.ex
2017	16	Permutation Promenade	count, op-code	day_16.ex
2017	17	Spinlock	sequence, simulation	day_17.ex
2017	18	Duet	data-modelling, op-code	day_18.ex
2017	23	Coprocessor Conflagration	op-code	day_23.ex
2018	3	No Matter How You Slice It	grid, set	day_03.ex
2018	7	The Sum of Its Parts	graph, simulation, topological-sort	day_07.ex
2018	25	Four-Dimensional Adventure	connectivity, constellation, graph	day_25.ex
2019	10	Monitoring Station	geometry, grid, sequence	day_10.ex
2020	11	Seating System	flood-fill, grid, parallel	day_11.ex
2020	13	Shuttle Search	math	day_13.ex
2020	14	Docking Data	bitwise, recursion	day_14.ex
2020	15	Rambunctious Recitation	dynamic-programming, sequence	day_15.ex
2020	16	Ticket Translation	ranges, validation	day_16.ex
2020	17	Conway Cubes	grid, simulation	day_17.ex
2020	18	Operation Order	parsing, recursion	day_18.ex
2020	21	Allergen Assessment	reduction, set	day_21.ex
2020	22	Crab Combat	game, recursion, simulation	day_22.ex
2020	24	Lobby Layout	hexagon, walk	day_24.ex
2021	9	Smoke Basin	connectivity, graph, grid	day_09.ex
2021	12	Passage Pathing	graph, pathfinding, recursion, traversal	day_12.ex
2021	16	Packet Decoder	bitwise	day_16.ex
2021	17	Trick Shot	physics, simulation	day_17.ex
2021	25	Sea Cucumber	grid, set	day_25.ex
2022	8	Treetop Tree House	graph, grid, traversal	day_08.ex
2022	9	Rope Bridge	grid, walk	day_09.ex
2022	10	Cathode-Ray Tube	op-code, visual-result	day_10.ex
2022	12	Hill Climbing Algorithm	graph, grid	day_12.ex
2022	20	Grove Positioning System	large-number, sequence	day_20.ex
2022	23	Unstable Diffusion	grid, walk	day_23.ex
2022	24	Blizzard Basin	a-star, graph, implicit-graph, pathfinding	day_24.ex
2022	25	Full of Hot Air	math	day_25.ex
2023	3	Gear Ratios	grid	day_03.ex
2023	7	Camel Cards	map, pattern-matching	day_07.ex
2023	13	Point of Incidence	palindrome, sliding-window	day_13.ex
2024	6	Guard Gallivant	cycle-detection, grid, simulation, slow	day_06.ex
2024	12	Garden Groups	geometry, union-find	day_12.ex
2024	18	RAM Run	binary-search, dijkstra, graph, grid	day_18.ex
2024	23	LAN Party	bron-kerbosch, clique, graph, lan-party, maximum-clique	day_23.ex
2025	2	Gift Shop	generation, math, simulation, string-manipulation	day_02.ex
2025	3	Lobby	greedy, optimization, stack	day_03.ex
2025	4	Printing Department	graph, grid, simulation	day_04.ex
2025	6	Trash Compactor	grid, math, parsing	day_06.ex
2025	9	Movie Theater	geometry	day_09.ex
2025	11	Reactor	dynamic-programming, graph	day_11.ex
2025	12	Christmas Tree Farm	geometry	day_12.ex

🔴 L

Year	Day	Title	Tags	Source
2015	20	Infinite Elves and Infinite Houses	optimization, sequence, sieve, slow	day_20.ex
2015	21	RPG Simulator 20XX	combinatorics, data-modelling, parsing, strategy	day_21.ex
2016	11	Radioisotope Thermoelectric Generators	graph, parsing, simulation, state-space	day_11.ex
2017	11	Hex Ed	hexagon	day_11.ex
2017	15	Dueling Generators	bitwise, math, optimization	day_15.ex
2018	5	Alchemical Reduction	reduction	day_05.ex
2018	8	Memory Maneuver	sequence, walk	day_08.ex
2020	19	Monster Messages	parsing, pattern-matching, recursion	day_19.ex
2020	23	Crab Cups	atomics, sequence	day_23.ex
2021	15	Chiton	graph	day_15.ex
2022	11	Monkey in the Middle	math, parsing	day_11.ex
2022	14	Regolith Reservoir	flood-fill, grid, implicit-graph	day_14.ex
2022	16	Proboscidea Volcanium	floyd-warshall, graph, optimization	day_16.ex
2022	17	Pyroclastic Flow	cycle-detection, simulation, tetris	day_17.ex
2023	14	Parabolic Reflector Dish	dynamic-programming, grid, math, rotation	day_14.ex
2023	16	The Floor Will Be Lava	dynamic-programming, grid	day_16.ex
2023	17	Clumsy Crucible	dijkstra, graph, grid, pathfinding, state-space	day_17.ex
2023	18	Lavaduct Lagoon	geometry	day_18.ex
2023	19	Aplenty	op-code, parsing	day_19.ex
2023	20	Pulse Propagation	cycles, graph, logic-circuit, math, simulation	day_20.ex
2023	21	Step Counter	cycles, graph, grid, math	day_21.ex
2023	25	Snowverload	graph, min-cut	day_25.ex
2025	7	Laboratories	dynamic-programming, grid	day_07.ex
2025	10	Factory	bitwise, dynamic-programming, graph, pathfinding	day_10.ex

💀 XL

Year	Day	Title	Tags	Source
2015	24	It Hangs in the Balance	ambiguous-solution, combinatorics	day_24.ex
2019	18	Many-Worlds Interpretation	bitwise, dijkstra, graph, implicit-graph, state-space-search	day_18.ex
2020	20	Jurassic Jigsaw	geometry, rotation	day_20.ex
2021	21	Dirac Dice	dynamic-programming	day_21.ex
2022	15	Beacon Exclusion Zone	geometry, interval-merging, optimization	day_15.ex
2022	18	Boiling Boulders	geometry, grid, set, traversal	day_18.ex
2022	19	Not Enough Minerals	optimization, parallel, search, slow	day_19.ex
2022	22	Monkey Map	geometry, walk	day_22.ex
2023	5	If You Give A Seed A Fertilizer	gb-tree, ranges	day_05.ex
2023	10	Pipe Maze	bfs, graph, grid	day_10.ex
2023	12	Hot Springs	dynamic-programming	day_12.ex
2023	22	Sand Slabs	ranges, stack	day_22.ex
2023	23	A Long Walk	graph, longest-path	day_23.ex
2023	24	Never Tell Me The Odds	geometry, refactor	day_24.ex