Advent of Code 2025

Every day done on the same day:

Times:

Day 1

Part 1: Brute Force

Part 2: Calculation + Brute Force

Day 2

Part 1: Prefilter + "smart" Brute Force

Part 2: "smart" Brute Force

Day 3

Part 1: Sliding Window + Brute Force

Part 2: Sliding Window + Brute Force

Day 4

Part 1: Brute Force

Part 2: Brute Force

Day 5

Part 1: Calculation

Part 2: Binary Tree for comfortable deduplication of ID ranges and recursive traversal for calculation

Day 6

Part 1: Calculation

Part 2: Ahhh yes... Cephalopod math

Day 7

Part 1: N² (not that bad -> only 3 columns and max all rows have to be checked for each splitter) Search from every splitter bottom to top until it is clear if it is reachable by a beam or not + Calculation

Part 2: Recursive calculation, basically DFS + Memoization

Day 8

Part 1: Forgot about Union Find and implemented something similar but bit more inefficient

Part 2: same as Part 1 but with more iterations

Day 9

Part 1: Brute Force (calculation of every possible area and selection of largest one)

Part 2: Ray Casting to check if all 4 corners are in the Polygon and checking if they are inside of an allowed area (didn't want to code the check for intersections of the vectors between the vertices, so I used a lil trick)

Day 10

Part 1: BFS + XOR logic

Part 2: Solving ILP without 3rd Party Library -> Gaussian Elimination + Null Space + Brute Force over search range to find free variables that minimize the number of button pushes

Day 11

Part 1: Brute Force

Part 2: DFS + Memoization + Calculation

Day 12

Part 1: Hmmm... yeah wasn't that hard as I thought it would be -> just calculation for each area

Part 2: Aaaaand that's it for this year \(^.^)/