AoC 2021 Day 25: Cucumbinator

Source: Sea Cucumber

Part 1: Load a grid of empty cells (.), east movers (>), and south movers (v). Each step, move all east movers than all south movers (only if they can this iteration). Wrap east/west and north/south. How many steps does it take the movers to get stuck?


AoC 2021 Day 19: Point Matchinator

Source: Snailfish

Part 1: You will be given a series of Scanners, each of which will tell you the location (from their point of view) of a series of Beacons. Each Scanner may be flipped or rotated in increments of 90 degrees in any direction. Determine where each Scanner and Beacon is by overlaying the maps (with at least pairwise 12 matches).


AoC 2021 Day 12: Submarine Spider

Source: Passage Pathing

Part 1: Given a list of edges in a bi-directional graph, count the number of paths from start to end such that nodes named with lowercase letters are visited once, and nodes with uppercase letters can be visited any number of times.


AoC 2021 Day 11: Octopus Flashinator

Source: Dumbo Octopus

Part 1: Simulate a grid of numbers such that on each tick: advance all numbers by 1, any number that increases over 9 will ‘flash’ and add 1 to all neighbors (recursively, but each cell can only flash once) and then reset to 0. Count the number of flashes in the first 100 ticks.


AoC 2021 Day 10: Chunkinator

Source: Syntax Scoring

Part 1: Given a sequence of () [] {}, and <> with nesting allowed. Find the first syntax error (where the wrong closing symbol is used). Scoring 3, 57, 1197, and 25137 respectively for each error, calculate the total error score.