I finished day 6 part 2 of #aoc2025. While I initially tried parsing forward through the lines of input, I eventually moved to parsing right to left. And again used reduce() to get the results of the problems.

#AdventOfCode2025 #AdventofCode

Finished work for the year so it's time to finally look into #AdventOfCode2025!

I just completed "Secret Entrance" - Day 1 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/1

I had fun applying reduce() to lists to solve day 6 part 1 of #aoc2025. I learned about reduce() while porting machine learning code to Linux on IBM Power many years back, but I've seldom used it.

#AdventofCode #AdventOfCode2025

I finished day 5 part 2 of #aoc2025. My first approach left me with overlapping ranges, so I had to revamp it. The working solution was much more elegant in addition to working!

#AdventofCode #AdventOfCode2025

https://christopherhimes.com/blog/2025/12/15/advent-of-code-2025-day9

Day 9: Movie Theater

#AdventOfCode #AdventOfCode2025 #Python

Throughout this year's #AdventOfCode event, I've been working on a single-line #Python program that solves *every* 2025 puzzle. The result is a >2,600 character beast I call "The Brahminy".

https://github.com/WinslowJosiah/adventofcode/blob/main/solutions/2025/brahminy.py

#programming #coding #AdventOfCode2025

For the last day of #AdventOfCode, I took a very simple and naive approach of: depth-first search.

Basically try all combinations until one fits. The trick to avoid a VERY long runtime is to filter out all cases where we already know from the start that the pieces (gifts) won't fit in the region, because their summed area exceeds the area of the region. Went for recursion this time around, because why not.

https://github.com/beeb/aoc-2025/blob/main/src/days/day12.rs

Overall, I really liked this year's puzzles. They weren't too hard which was refreshing compared to the last couple of years. I doubt many people really like those extremely hard to solve problems that take one day or more for anyone who isn't a genius (but I might be wrong). For me, it struck a nice balance and it felt rewarding enough to scratch my decembre puzzle itch! I also enjoyed the shorter run, I usually got quite burnt out by the end, especially with all the social functions towards the end of the month.

#AoC #AoC205 #AdventOfCode2025 #RustLang #rust

Day 11 of #AdventOfCode is a classical graph problem like we're used to from previous years.

Unlike previously, I immediately thought of checking what the graph looked like with a visualization tool. Luckily, `petgraph` allows to export a graphviz file which can be then used to visualize the nodes and edges.

From that, it was clear that a few nodes were acting as "bridges" between largers subnets of nodes with no particular arrangement besides being directed towards the next "bridge" layer. Those bridge layers comprised 4 to 5 nodes in my input, and were the only ones with more than 6 incoming edges, so I used that as my filter criterion.

To gather them, I sorted the graph in topological order and chunked them by their position offset compared to the previous node. When doing this, all the nodes from a bridge layer end up being at most 20 positions away from the previous node in the sorted list.

Finally, I progressed through each subnet, collecting information about how many paths lead to each one of the end layer's nodes. By multiplying with all the paths leading to each start layer's node, we get the overall total number of paths.

https://github.com/beeb/aoc-2025/blob/main/src/days/day11.rs

#AoC #AoC2025 #AdventOfCode2025 #RustLang #rust