Advent of Code (2021) Day Solution Day 1: Sonar Sweep Code Day 2: Dive! Code Day 3: Binary Diagnostic Code Day 4: Giant Squid Code Day 5: Hydrothermal Venture Code Day 6: Lanternfish Code Day 7: The Treachery of Whales Code Day 8: Seven Segment Search Code Day 9: Smoke Basin Code Day 10: Syntax Scoring Code Day 11: Dumbo Octopus Code Day 12: Passage Pathing Code Day 13: Transparent Origami Code Day 14: Extended Polymerization Code Day 15: Chiton Code Day 16: Packet Decoder Code Day 17: Trick Shot Code Day 18: Snailfish Code Day 19: Beacon Scanner Code Day 20: Trench Map Code Day 21: Dirac Dice Code Day 22: Reactor Reboot Code Day 23: Amphipod Code Day 24: Arithmetic Logic Unit Code Day 25: Sea Cucumber Code