- Day 1: Trebuchet?! [problem] [solution][test]
- Day 2: Cube Conundrum [problem] [solution][test]
- Day 3: Gear Ratios [problem] [solution][test]
- Day 4: Scratchcards [problem] [solution][test]
- Day 5: If You Give A Seed A Fertilizer [problem] [solution][test]
- Day 6: Wait For It [problem] [solution][test]
- Day 7: Camel Cards [problem] [solution][test]
- Day 8: Haunted Wasteland [problem] [solution][test]
- Day 9: Mirage Maintenance [problem] [solution][test]
- Day 10: Pipe Maze [problem] [solution][test]
- Day 11: Cosmic Expansion [problem] [solution][test]
- Day 12: Hot Springs [problem] [solution][test]
- Day 13: Point of Incidence [problem] [solution][test]
- Day 14: Parabolic Reflector Dish [problem] [solution][test]
- Day 15: Lens Library [problem] [solution][test]
- Day 16: The Floor Will Be Lava [problem] [solution][test]
- Day 17: Clumsy Crucible [problem] [solution][test]
- Day 18: Lavaduct Lagoon [problem] [solution][test]
- Day 19: Aplenty [problem] [solution][test]
- Day 20: Pulse Propagation [problem] [solution][test]
- Day 21: Step Counter [problem] [solution][test]
- Day 22: Sand Slabs [problem] [solution][test]
- Day 23: A Long Walk [problem] [solution][test]
- Day 1: None [problem] [solution][test]
- Day 2: None [problem] [solution][test]
- Day 3: None [problem] [solution][test]
- Day 4: None [problem] [solution][test]
- Day 5: None [problem] [solution][test]
- Day 6: None [problem] [solution][test]
- Day 7: None [problem] [solution][test]
- Day 9: None [problem] [solution][test]
- Day 10: None [problem] [solution][test]
- Day 11: None [problem] [solution][test]
- Day 12: None [problem] [solution][test]
- Day 14: None [problem] [solution][test]
- Day 17: None [problem] [solution][test]
- Day 18: None [problem] [solution][test]
- Day 22: Monkey Map [problem] [solution][test]
- Day 23: Unstable Diffusion [problem] [solution][test]
- Day 25: Full of Hot Air [problem] [solution][test]
- Day 1: Sonar Sweep [problem] [solution][test]
- Day 2: Dive! [problem] [solution][test]
- Day 3: Binary Diagnostic [problem] [solution][test]
- Day 4: Giant Squid [problem] [solution][test]
- Day 5: Hydrothermal Venture [problem] [solution][test]
- Day 6: Lanternfish [problem] [solution][test]
- Day 7: The Treachery of Whales [problem] [solution][test]
- Day 8: Seven Segment Search [problem] [solution][test]
- Day 9: Smoke Basin [problem] [solution][test]
- Day 10: Syntax Scoring [problem] [solution][test]
- Day 11: Dumbo Octopus [problem] [solution][test]
- Day 12: Passage Pathing [problem] [solution][test]
- Day 13: Transparent Origami [problem] [solution][test]
- Day 14: Extended Polymerization [problem] [solution][test]
- Day 15: Chiton [problem] [solution][test]
- Day 16: Packet Decoder [problem] [solution][test]
- Day 17: Trick Shot [problem] [solution][test]
- Day 18: Snailfish [problem] [solution][test]
- Day 19: Beacon Scanner [problem] [solution][test]
- Day 20: Trench Map [problem] [solution][test]
- Day 21: Dirac Dice [problem] [solution][test]
- Day 22: Reactor Reboot [problem] [solution][test]
- Day 23: Amphipod [problem] [solution][test]
- Day 24: Arithmetic Logic Unit [problem] [solution][test]
- Day 25: Sea Cucumber [problem] [solution][test]
- Day 1: Report Repair [problem] [solution]
- Day 2: Password Philosophy [problem] [solution]
- Day 3: Toboggan Trajectory [problem] [solution]
- Day 4: Passport Processing [problem] [solution]
- Day 5: Binary Boarding [problem] [solution]
- Day 6: Custom Customs [problem] [solution]
- Day 7: Handy Haversacks [problem] [solution]
- Day 8: Handheld Halting [problem] [solution]
- Day 9: Encoding Error [problem] [solution]
- Day 10: Adapter Array [problem] [solution]
- Day 11: Seating System [problem] [solution]
- Day 12: Rain Risk [problem] [solution]
- Day 13: Shuttle Search [problem] [solution]
- Day 14: Docking Data [problem] [solution]
- Day 15: Rambunctious Recitation [problem] [solution]
- Day 16: Ticket Translation [problem] [solution]
- Day 17: Conway Cubes [problem] [solution]
- Day 18: Operation Order [problem] [solution]
- Day 19: Monster Messages [problem] [solution]
- Day 20: Jurassic Jigsaw [problem] [solution]
- Day 21: Allergen Assessment [problem] [solution]
- Day 22: Crab Combat [problem] [solution]
- Day 23: Crab Cups [problem] [solution]
- Day 24: Lobby Layout [problem] [solution]
- Day 25: Combo Breaker [problem] [solution]
- Day 1: The Tyranny of the Rocket Equation [problem] [solution][test]
- Day 2: 1202 Program Alarm [problem] [solution][test]
- Day 3: Crossed Wires [problem] [solution][test]
- Day 4: Secure Container [problem] [solution][test]
- Day 5: Sunny with a Chance of Asteroids [problem] [solution][test]
- Day 6: Universal Orbit Map [problem] [solution][test]
- Day 7: Amplification Circuit [problem] [solution][test]
- Day 8: Space Image Format [problem] [solution][test]
- Day 10: Monitoring Station [problem] [solution][test]
- Day 1: Chronal Calibration [problem] [solution][test]
- Day 2: Inventory Management System [problem] [solution][test]
- Day 3: No Matter How You Slice It [problem] [solution][test]
- Day 4: Repose Record [problem] [solution][test]
- Day 5: Alchemical Reduction [problem] [solution][test]
- Day 7: The Sum of Its Parts [problem] [solution][test]
- Day 1: Inverse Captcha [problem] [solution][test]
- Day 2: Corruption Checksum [problem] [solution][test]
- Day 3: Spiral Memory [problem] [solution][test]
- Day 4: High-Entropy Passphrases [problem] [solution][test]
- Day 5: A Maze of Twisty Trampolines, All Alike [problem] [solution][test]
- Day 6: Memory Reallocation [problem] [solution][test]
- Day 7: Recursive Circus [problem] [solution][test]
- Day 8: I Heard You Like Registers [problem] [solution][test]
- Day 9: Stream Processing [problem] [solution][test]
- Day 10: Knot Hash [problem] [solution][test]
- Day 11: Hex Ed [problem] [solution][test]
- Day 12: Digital Plumber [problem] [solution][test]
- Day 13: Packet Scanners [problem] [solution][test]
- Day 14: Disk Defragmentation [problem] [solution][test]
- Day 15: Dueling Generators [problem] [solution][test]
- Day 16: Permutation Promenade [problem] [solution][test]
- Day 17: Spinlock [problem] [solution][test]
- Day 18: Duet [problem] [solution][test]
- Day 19: A Series of Tubes [problem] [solution][test]
- Day 20: Particle Swarm [problem] [solution][test]
- Day 21: Fractal Art [problem] [solution][test]
- Day 22: Sporifica Virus [problem] [solution][test]
- Day 23: Coprocessor Conflagration [problem] [solution][test]
- Day 24: Electromagnetic Moat [problem] [solution][test]
- Day 25: The Halting Problem [problem] [solution][test]
- Day 1: No Time for a Taxicab [problem] [solution][test]
- Day 2: Bathroom Security [problem] [solution][test]
- Day 3: Squares With Three Sides [problem] [solution][test]
- Day 4: Security Through Obscurity [problem] [solution][test]
- Day 5: How About a Nice Game of Chess? [problem] [solution][test]
- Day 6: Signals and Noise [problem] [solution][test]
- Day 7: Internet Protocol Version 7 [problem] [solution][test]
- Day 8: Two-Factor Authentication [problem] [solution][test]
- Day 9: Explosives in Cyberspace [problem] [solution][test]
- Day 10: Balance Bots [problem] [solution][test]
- Day 11: Radioisotope Thermoelectric Generators [problem] [solution][test]
- Day 12: Leonardo's Monorail [problem] [solution][test]
- Day 13: A Maze of Twisty Little Cubicles [problem] [solution][test]
- Day 14: One-Time Pad [problem] [solution][test]
- Day 15: Timing is Everything [problem] [solution][test]
- Day 16: Dragon Checksum [problem] [solution][test]
- Day 17: Two Steps Forward [problem] [solution][test]
- Day 18: Like a Rogue [problem] [solution][test]
- Day 19: An Elephant Named Joseph [problem] [solution][test]
- Day 20: Firewall Rules [problem] [solution][test]
- Day 21: Scrambled Letters and Hash [problem] [solution][test]
- Day 22: Grid Computing [problem] [solution][test]
- Day 23: Safe Cracking [problem] [solution][test]
- Day 24: Air Duct Spelunking [problem] [solution][test]
- Day 25: Clock Signal [problem] [solution][test]
- Day 1: Not Quite Lisp [problem] [solution][test]
- Day 2: I Was Told There Would Be No Math [problem] [solution][test]
- Day 3: Perfectly Spherical Houses in a Vacuum [problem] [solution][test]
- Day 4: The Ideal Stocking Stuffer [problem] [solution][test]
- Day 5: Doesn't He Have Intern-Elves For This? [problem] [solution][test]
- Day 6: Probably a Fire Hazard [problem] [solution][test]
- Day 7: Some Assembly Required [problem] [solution][test]
- Day 8: Matchsticks [problem] [solution][test]
- Day 9: All in a Single Night [problem] [solution][test]
- Day 10: Elves Look, Elves Say [problem] [solution][test]
- Day 11: Corporate Policy [problem] [solution][test]
- Day 12: JSAbacusFramework.io [problem] [solution][test]
- Day 13: Knights of the Dinner Table [problem] [solution][test]
- Day 14: Reindeer Olympics [problem] [solution][test]
- Day 15: Science for Hungry People [problem] [solution][test]
- Day 16: Aunt Sue [problem] [solution][test]
- Day 17: No Such Thing as Too Much [problem] [solution][test]
- Day 18: Like a GIF For Your Yard [problem] [solution][test]
- Day 19: Medicine for Rudolph [problem] [solution][test]
- Day 20: Infinite Elves and Infinite Houses [problem] [solution][test]
- Day 21: RPG Simulator 20XX [problem] [solution][test]
- Day 22: Wizard Simulator 20XX [problem] [solution][test]
- Day 23: Opening the Turing Lock [problem] [solution][test]
- Day 24: It Hangs in the Balance [problem] [solution][test]
- Day 25: Let It Snow [problem] [solution][test]