Day 1 of Advent of Code 2025 is a neat exercise in modular arithmetic, where you track a circular dial and count how often it hits zero. Part 1 counts only the zeros landed on at the end of rotations, and Part 2 upgrades that to count every click that passes through zero mid-rotation too. In this …

Adding a human-in-the-loop step to a LangGraph flow is an easy way to improve quality and control without adding branching or complexity. In this post we will build a tiny three-node graph that drafts copy with an LLM, pauses for human feedback, and then revises the draft, using LangGraph’s …

Advent of Code 2025 is almost here, and this year I am aiming squarely at speed and optimisation across all 12 puzzles using Python and UV. I will publish a short post every day covering the approach and performance choices, and you are very welcome to join in using whichever language you want to …

The next rules to implement for the Sudoku solver are called wing rules. There are a few of these rules used in solving Sudoku, but some are hard to identify and are for very advanced solves. The two needed to solve most Sudoku puzzles are called XY-Wing and XYZ-Wing:

• XY-Wing uses a pivot cell with …

Style guides are not bikeshedding; they are seatbelts that stop simple edits turning into catastrophic bugs. The infamous #gotofail incident shows how a tiny deviation from a basic rule like “always use braces” can undermine critical security checks, and how automated style enforcement …

Day 7 of Advent of Code 2024 boils down to testing all left-to-right operator choices between fixed numbers and summing the targets that are achievable, and a compact base-k iterator in Ruby keeps both parts small, clear, and fast. You can browse the rest of this series under Advent of Code. The …

Conditional edges let your LangGraph apps make decisions mid-flow, so today we will branch our simple joke generator to pick a pun or a one-liner while keeping wrap_presentation exactly as it was. In the previous post we built a two-node graph with joke_writer and wrap_presentation, and now we will …

LangGraph makes it easy to wire simple, reliable LLM workflows as graphs, and in this post we will build a tiny two‑node graph that turns a topic into a joke and then formats it as a mini conversation ready to display or send. By the end, you will have a minimal Python project with a typed JokeState …

First I’d like to apologise that this is the second week in a row that I’ve covering Advent of Code. I’ve not had as much time to write this week as I’d like to. I will try to get something more substantial out in the following weeks.

Day 6 of Advent of Code 2024 turned out …

Day 5 of Advent of Code 2024 is all about enforcing page ordering rules and pulling the “middle” value out at the right time, and my Ruby solution keeps it tidy with a small helper, a simple validator, and a lightweight reordering trick for the second half. If you want to browse …

The next rules to implement for the Sudoku solver are called the fish rules. There are three versions of these rules but they all share the same principles:

• X-Wing works with a 2x2 fish pattern.
• Swordfish works with a 3x3 fish pattern.
• Jellyfish works with a 4x4 fish pattern.

If you like this post …

Day 4 of Advent of Code 2024 turns a simple word search into a neat grid‑traversal exercise, and my Ruby solution keeps it readable, fast, and precise. This post explains the requirements for both parts, then walks through how the code solves them, including how diagonals and boundaries are handled. …