Advent of Code (2016) Day Solution Day 1: No Time for a Taxicab Code Day 2: Bathroom Security Code (C) Day 3: Squares With Three Sides Code (C) Day 4: Security Through Obscurity Code Day 5: How About a Nice Game of Chess? Code Day 6: Signals and Noise Code Day 7: Internet Protocol Version 7 Code Day 8: Two-Factor Authentication Code Day 9: Explosives in Cyberspace Code Day 10: Balance Bots Code Day 11: Radioisotope Thermoelectric Generators Code Day 12: Leonardo's Monorail Code Day 13: A Maze of Twisty Little Cubicles Code Day 14: One-Time Pad Code Day 15: Timing is Everything Code Day 16: Dragon Checksum Code Day 17: Two Steps Forward Code Day 18: Like a Rogue Code Day 19: An Elephant Named Joseph Code Day 20: Firewall Rules Code Day 21: Scrambled Letters and Hash Code Day 22: Grid Computing Code Day 23: Safe Cracking Code Day 24: Air Duct Spelunking Code Day 25: Clock Signal Code