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Day 2 was all about spotting playful ID patterns inside huge numerical ranges. Here’s how both parts came together. Input parsing shared by both parts The puzzle input is one comma-separated line of inclusive ranges (start-end). I parse everything as...
For Day 1 I had to open a safe with a dial numbered 0–99. Here’s how both halves of the puzzle fell. Part 1 – Counting end-of-rotation zeros The dial starts at 50 and each instruction looks like L68 or R48. I only needed to know how many times the di...
I spent Day 3 hanging out in the lobby with a pile of battery banks and a stubborn escalator. Here is how I cracked both puzzles using a pair of lean JavaScript scripts (part1.js and part2.js). Part 1 – Two batteries, one number Each bank is a string...
Forklifts, paper rolls, and lots of adjacency checks: Day 4 turned into a neat graph-like puzzle. Here’s how I solved both parts and what their complexity looks like. Part 1 – Finding accessible rolls Each roll of paper is represented by @ on a grid....
Day 6 brings us into a garbage compactor where we meet a family of cephalopods. To pass the time while they open the door, we help the youngest one with her math homework. The puzzle involves parsing a 2D grid of characters representing math problems...
Day 8 was basically a geometric Kruskal party. Every junction box is a point in 3D space, and connecting two points merges their electrical circuits. Part 1 stops after the 1000 closest connections; Part 2 runs until everything is fused into one mega...