Code for www.adventofcode.com in Python.
Day 1 - Calorie Counting - Sum groups of numbers
Day 2 - Rock Paper Scissors
Day 1 p1 p2 - Sonar Sweep -- Increasing numbers
Day 2 p1 p2 - Dive! -- Move submarine
Day 3 p1 p2 - Binary Diagnostics! -- Most common digit
Day 4 p1 p2 - Giant Squid! -- Bingo Cards
Day 5 p1 p2 - Hydrothermal Venture!
Day 6 - Lanternfish -- Dynamic Programming
Day 7 - The Treachery of Whales
Day 8 - Seven Segment Search -- Find out what segments match
Day 9 - Smoke Basin -- Region coloring
Day 10 - Syntax Scoring -- Compiler matching
Day 11 and Day 11 with Numpy - Dumbo Octopus -- Grid flashing
Day 12 and super fast DFS with memoization - Passage Pathing -- Find all paths
Day 13 - Transparent Origami -- Fold Grid
Day 14 and an alternative DP/memoization solution - Extended Polymerization -- Expanding strings
Day 15 - Chiton -- Shortest path (Dynamic Programming and Djikstra)
Day 16 Part 1 and Day 16 Part 1 - Packet Decoder -- Parse packets
Day 17 - Trick shot -- Predict trajectory
Day 18 - Snailfish -- Binary Tree
Day 19 - Beacon Scanner -- Overlapping scanners
Day 20 - Trench Map -- Image enhancement
Day 21 - Dirac Dice -- Dynamic programming
Day 22 - Reactor Reboot -- Overlapping cubes
Day 23 - Amphipod -- A* search in amphipod maze
Day 24 - Arithmetic Logic Unit -- Translate and optimize ALU code
Day 25 - Sea Cucumber -- East and Down moving sea cucumbers
Day 1 - Report Repair -- Find expenses adding up to 2020
Day 2 - Password Philosophy -- Password validation
Day 3 - Toboggan Trajectory -- Count trees
Day 4 - Passport Processing -- Validate Passports
Day 5 - Binary Boarding -- Binary boarding passes
Day 6 - Custom Customs -- Find commonalities in groups of answers
Day 7 - Handy Haversacks -- Calculating recursive bags needed
Day 8 - Handheld Halting -- Implement a basic assembly compiler
Day 9 - Encoding Error -- Find sums in lists
Day 10 - Adapter Array -- Find combinations of adapters
Day 11 - Seating System -- Alternate grid based on adjacent and visible
Day 12 - Rain Risk -- moves and directions
Day 13 - Shuttle Search -- chinese remainders and modulo operations
Day 14 - Docking Data -- Bit masks
Day 15 - Rambunctious Recitation -- Calculate when a number was last seen
Day 16 - Ticket Translation -- Validate unreadable flight tickets
Day 17 - Conway Cubes -- 3D and 4D Conway Cubes
Day 18 - Operation Order -- Build a calculator with reverse operator order
Day 19 - Monster Messages -- Rules Engine
Day 20 - Jurassic Jigsaw -- rotate pieces, find sea monsters - This one was a nightmare
Day 21 - Allergen Assessment -- finding allergens, list intersections
Day 22 - Crab Combat -- simple card game
Day 23 - Crab Cups -- circular game of cups - slow with list, super fast with dicts
Day 24 - Lobby Layout -- hexagonal tiles and paths - reducing paths
Day 25 - Combo Breaker -- RFID decryption
Day 1 - The Tyranny of the Rocket Equation -- Calculate Fuel
Day 2 - 1202 Programming Alarm -- IntCode computer - Part I
Day 3 - Crossing Wires -- (R32,L43...)
Day 4 - Secure Container -- Passwords
Day 5 - Sunny with a Chance of Asteroids -- IntCode - Part II
Day 6 - Universal Orbit Map -- Calculate number of orbits A)B
Day 7 - Amplification Circuit -- IntCode - Part III
Day 8 - Space Image Format -- Layered images
Day 9 - Sensor Boost -- IntCode IV
Day 10 - Monitoring Station -- Vaporize asteroids in grid
Day 11 - Space Police -- IntCode V
Day 12 - The N-Body Problem -- calculate orbits and gravity
Day 13-1 - Care Package -- IntCode VI -- draw arcade games
Day 14 - Space Stoichiometry -- Create FUEL from ORE
Day 15 - Oxygen System -- IntCode VII -- Maze
Day 16 - Flawed Frequency Transmission -- Binomial code - crazy hard
Day 17 - Set and Forget -- IntCode VIII - vacuum cleaner
Day 1 - Chronal Calibration -- Frequency changes
Day 2 - Inventory Management System -- Candidate box IDs, and common letters
Day 3 - No Matter How You Slice It -- Claim santa fabric
Day 4 - Repose Record -- Sleeping guard logs
Day 5 - Alchemical Reduction -- Reduce strings
Day 6 - Chronical Coordinates -- Find largest area
Day 7 - The Sum of Its Parts -- Calculate chain of events
Day 8 - Memory Maneuver -- Read file contents with meta data
Day 9 - Marble Mania -- Play a game of % 23 marbles
Day 10 - The stars align -- Stars moving to show a message
Day 11 - Chronal Charge -- Sum of 3x3 area
Day 12 - Subterranean Sustainability -- ##..# => .
Day 13 - Mine cart madness -- Train tracks.
Day 14 - Chocolate Charts -- Calculate recipe sums.
Day 16 - Chronal Classification -- Register program.
Day 17 - Resevoir Research -- Water flow (with pygame animations)
Day 18 - Settlers of The North Pole -- Morph the earth based on adjacent squares - part II repeating pattern
Day 19 - Go With The Flow -- Reverse engineering op code - find divisors
Day 20 - A Regular Map -- Regular expression paths - find shortest path
Day 21 - Chronal Conversion -- Reverse engineer op code - optimize
Day 22 - Mode Maze -- Maze with different areas and tools - dijkstra's algorithm
Day 23 - Experimental Emergency Teleportation -- Range in 3D space - PART II is incomplete
Day 1 - Captcha -- Sum if same as next
Day 2 - Corruption Checksum -- Sum of differences and divisors
Day 3 - Spiral Memory -- Count steps from center
Day 4 - High-Entropy Passphrases -- Valid passphrases
Day 5 - A Maze of Twisty Trampolines, All Alike -- Int maze
Day 6 - Memory Reallocation -- Distributing weight
Day 7 - Recursive Circus -- Finding chains
Day 8 - I Heard You Like Registers -- Execute jumps
Day 9 - Stream Processing -- <garbage> {group}
Day 10 - Knot Hash -- Elves hashing function
Day 11 - Hex Ed -- Reduce hexagonal path
Day 12 - Digital Plumber -- Find islands of numbers
Day 13 - Packet Scanners -- Scan layers of packages
Day 14 - Disk Defragmentation -- Knot Hash, and clustering binary regions
Day 15 - Dueling Generators -- Checking pairs of binary numbers
Day 16 - Permutation Promenade -- Compiler for program dance
Day 17 - Spinlock -- Crazy spinlock algorithm
Day 18 - Duet -- Compiler for sender/receiver
Day 19 - A Series of Tubes -- Follow a path
Day 20 - Particle Swarm -- Accelerate Particles
Day 21 - Fractal Art -- Replace rows by rules
Day 22 - Sporifica Virus -- Virus infection
Day 23 - Coprocessor Conflagation -- Simple compiler
Day 24 - Electromagnetic Moat -- Domino chain
Day 25 - The Halting Problem -- Turing machine
Day 1 - No Time for a Taxicab -- Rotate Right and Left
Day 2 - Bathroom Security -- Keypads
Day 3 - Squares With Three Sides -- Good Triangles
Day 4 - Security Through Obscurity -- encrypted rooms
Day 5 - How About a Nice Game of Chess? -- MD5
Day 6 - Signals and Noise -- Most common in each column
Day 7 - Internet Protocol Version 7 -- Validate IP address
Day 8 - Two-Factor Authentication -- Light screen
Day 9 - Explosives in Cyberspace -- Decompressing strings
Day 10 - Balance Bots -- Bots moving numbers
Day 11 - Radioisotope Thermoelectric Generators - Move elevator up and down (other peoples code)
Day 12 - Leonardo's Monorail -- mini compiler
Day 13 - A Maze of Twisty Little Cubicles -- maze
Day 14 - One-Time Pad -- MD5 hash
Day 15 - Timing is everything -- Rotating discs
Day 16 - Dragon Checksum -- Dragon curve random data
Day 17 - Two Steps Forward -- Path to Vault
Day 18 - Like a Rogue -- Traps and Safes
Day 19 - An Elephant Named Joseph -- Stealing gifts in a circle
Day 20 - Firewall Rules -- Count available IPs
Day 21 - Scrambled Letters and Hash -- Scramble letters according to instructions
Day 22 - Grid Computing -- Sliding puzzle
Day 23 - Safe Cracking -- Simple compiler with toggle
Day 24 - Air Duct Spelunking -- Find best path visiting all numbers
Day 25 - Clock Signal -- More bunny compiler
Day 1 - Not Quite Lisp -- Calculate ())))(
Day 2 - I Was Told There Would Be No Math -- Ribbons and Paper
Day 3 - Perfectly Spherical Houses in a Vacuum -- ^v^v^v^v^v
Day 4 - The Ideal Stocking Stuffer -- MD5
Day 5 - Doesn't He Have Intern-Elves For This? -- Passwords
Day 6 - Probably a Fire Hazard -- Grid Board
Day 7 - Some Assembly Required -- Bitwise Logic gates
Day 8 - Matchsticks -- Calculate escape characters
Day 9 - All in a Single Night -- Shortest route between cities
Day 10 - Elves Look, Elves Say -- Look and say numbers
Day 11 - Corporate Policy -- Password Regexps
Day 12 - JSAbacusFramework.io -- Finding numbers in string
Day 13 - Knights of the Dinner Table -- Find optimal seating
Day 14 - Reindeer Olympics -- How long did the winning deer travel
Day 15 - Science for Hungry People -- Best cookie ingredient combo
Day 16 - Aunt Sue -- Find out which Aunt Sues
Day 17 - No Such Thing as Too Much -- Combos of egg nog containers
Day 18 - Like a GIF For Your Yard -- Conways game of life
Day 19 - Medicine for Rudolph -- Replace substrings
Day 20 - Infinite Elves and Infinite Houses -- Prime factors
Day 21 - RPG Simulator 20XX -- Armor and Damage
Day 22 - Wizard Simulator 20XX -- Mana and damage
Day 23 - Opening the Turning Lock -- Tiny compiler
Day 24 - It hangs in the balance -- Balancing packages
Day 25 - Let it snow -- Calculate code