The earliest memory I have of ‘programming’ is in the early/mid 90s when my father brought home a computer from work. We could play games on it … so of course I took the spreadsheet program he used (LOTUS 123, did I date myself with that?) and tried to modify it to print out a helpful message for him. It … halfway worked? At least I could undo it so he could get back to work…

After that, I picked up programming for real in QBASIC (I still have a few of those programs lying around), got my own (junky) Linux desktop from my cousin, tried to learn VBasic (without a Windows machine), and eventually made it to high school… In college, I studied computer science and mathematics, mostly programming in Java/.NET, although with a bit of everything in the mix. A few of my oldest programming posts on this blog are from that time.

After that, on to grad school! Originally, I was going to study computational linguistics, but that fell through. Then programming languages (the school’s specialty). And finally I ended up studying censorship and computer security… before taking a hard turn into the private sector to follow my PhD advisor.

Since then, I’ve worked in the computer security space at a couple of different companies. Some don’t exist any more, some you’ve probably heard of. I still program for fun too, and not just in security.

But really, I still have a habit of doing a little bit of everything. Whatever seems interesting at the time!

CodeCrafters: Build Myself an Interpreter

2024-09-04

Didn’t I just do one of these? Well, yes. Yes I did. But I love building compilers and interpreters, so when I saw this one was in beta (and thus free 😉), I had to try it! It’s directly an implemention of the Lox languages from the Crafting Interpreters website / book (my review), if incomplete. By the end of the lesson, we’ll have: A tokenizer that handles parentheses, braces, operators (single and multiple character), whitespace, identifiers, string literals, numeric literals, and keywords A parser that can take those tokens and build an abstract syntax tree using recursive descent parsing A simple tree walking interpreter for some subset of the language It doesn’t handle all of the syntax (yet).

Solving Cosmic Express

2024-09-02

Another Rust Solvers puzzle: Cosmic Express. Basically, it’s a routefinding puzzle. You have a train that needs a track from entrance to exit, picking up and dropping off cargo on the way.

It’s actual a relatively simple puzzle, so far as things go, but one thing that’s interesting from a solving perspective is that branching paths really don’t work great with my solver code. Paths just have a crazy branching factor when compared to (for example) playing one of a handful of cards.

But it’s still an interesting puzzle!

CodeCrafters: Build Myself a Grep

2024-08-28

I recently stumbled across CodeCrafters again¹. In a nutshell, they give a number of ‘Build Your Own…’ courses, each of which will automatically create a repo for you, guide you through solving the program step by step, and provide some feedback on the way.

On one hand, it’s a freemium (one problem a month is free) / paid service. I wish they had tiers. I really think their monthly fee is a bit steep for what they offer (we’ll come back to that). But on the other hand, it’s a neat tool and I’ve been wanting some more larger programming projects to learn more Rust on, so away we go!

First up, grep!

TestIT - Integration Testing for My Rust Solvers

2024-08-19

One of the problems (of a sorts) I’ve been having with my series on Rust Solvers is that, for each input puzzle, I need a way to save one or more ‘known good’ solutions so that when I change and add new functionality, I can verify that I’ve either not changed the solution or found another valid one.

Integration tests as it were.

So far, I’d been building this into each solution. While this worked perfectly fine, it’s a bit annoying to copy and paste to each binary, and then have to edit each test case with the answers.

An example run

Enter: testit:

# First run, without --db/--save for previous runs
$ testit \
  --command "./target/release/golf-peaks" \
  --files "data/golf-peaks/**/*.txt" \
  --timeout 60

data/golf-peaks/1-1.txt: New success:
1-↗

===

data/golf-peaks/1-10.txt: New success:
1-↘ 3-↙ 2-↘

===

...

data/golf-peaks/9-8.txt: New success:
1/3-↘ 1/2-↖ 1/↗ 2/1-↖ 1/1-↗

===

data/golf-peaks/9-9.txt: New success:
1-↗ 1/↘ 1-↘ 4-↗ 3-↘ 1/1-↗

===

data/golf-peaks/Credits.txt: New success:
4-↖ 5-↗ 3-↗ 6-↘

===


Summary:
	Successes: 121 (121 new)
	Failures: 0
	Timeouts: 0

# Later runs
$ testit \
  --command "./target/release/golf-peaks" \
  --files "data/golf-peaks/**/*.txt" \
  --timeout 60 \
  --db testit/golf-peaks.json \
  --save


Summary:
	Successes: 121 (0 new)
	Failures: 0
	Timeouts: 0

Pretty cool, I do think. 😄

The Golf (Peaks) of Solving

2024-06-17

Another day (week? month?), another puzzle game.

This time around, we’re going to solve Golf Peaks. I picked this up a while ago on iOS, but only recently on Steam. It’s a cute little puzzle game themed around minigolf.

Basically, you’re on a grid and you have to get the ball (in the bottom in that screenshot above) to the flag (currently at the top). You have a set list of moves you can take, styled as cards–all of which either move a certain number of tiles in a specific direction or possibly jump into the air (and fly over obstacles).

It gets more complicated from there, but hopefully you have the basic idea. 😄

Solving Sokobond

2024-04-06

Another solver that I’ve been working on, after A Good Snowman Is Hard To … Solve?. This time, we have Sokobond! It’s a Sokobon… but with chemical bonds! Yeah, that’s a really good title.

The basic idea is you have a field of elements with (chemical accurate) free electrons):

A basic level

Here we have 4 hydrogens (1 bond each) and a carbon (4 bonds). It should seem pretty obvious that the carbon should end up with a hydrogen on each end. The one last bit of interest: the element with the dashed border is the one we actually control, that will never change.

This eventually gets more complicated, adding:

Modifiers that are placed on the map between squares:
- One that strengthens bonds, turning a single bond into double into triple
- One that weakens bonds, turning triple to double to single or breaking single bonds
- One that rotates bonds as you move by it
More elements, eventually hydrogen (1), oxygen (2), nitrogen (3), carbon (4), and helium (0)
Solutions that require forming multiple elements at the same time

It’s a pretty neat puzzle game with 144 levels of increasing difficulty. Perfect to solve.

A Good Snowman Is Hard To ... Solve?

2024-03-28

I enjoy puzzle games. I especially enjoy letting computers solve them for me 😄. Once upon a time, I set up a framework for solving random things. Let’s solve some more.

Today: A Good Snowman Is Hard To Build

It’s a Sokoban about making snowmen! You can push snowballs of three sizes around, collecting snow if you roll over it. You can push smaller snowballs onto bigger ones, stacking them. Or back off, in order to get around one another.

And that’s really it.

There are some interesting twists (multiple snowmen, the ability to leave and re-enter levels, and even a whole second ‘hard mode’), but at a basic level, it’s just pushing.

Infinite Craft Bot

2024-03-14

You’ve probably seen Neil.fun’s Infinite Craft game somewhere on the internet. If not, in a nutshell:

You start with 4 blocks: Earth, Fire, Water, and Wind.
You can combine any two blocks, for example:
- Earth + Water = Plant
- Plant + Fire = Smoke
- Smoke + Smoke = Cloud

That’s… pretty much it, from a gameplay perspective. There’s not really any goal, other than what you set yourself (try to make Cthulhu!). Although if you manage to find something no one has ever made before, you get a neat little note for it!

So wait, what do I mean by ‘something no one has ever seen before’?

Well, if two elements have ever been combined by anyone before, you get a cached response. Barring resets of the game (no idea if / how often this has happened, but I assume it has), if A + B = C for you, A + B = C for everyone.

And here’s the fun part: if you find a combination no one has ever found before: Neil.fun will send the combination out to an LLM to generate the new answer. The specific prompt isn’t public (so far as I know), but essentially what that means is that you have a basically infinite crafting tree¹!

So of course seeing something like this I want to automate it. 😄

Advent of Code 2023 - Testing and Timing

2023-12-28

A quick follow up to Advent of Code 2023: testing and timing.

It’s been bothering me a bit that I haven’t had a generic way to run tests and timing on every problem as I’m going.

So let’s fix it!

AoC 2023 Day 25: Graph Splitinator

2023-12-25

Source: Day 25: Snowverload

Full solution for today (spoilers!)

Part 1

Given an undirected graph, find 3 edges that split the graph into two connected components. Return the product of the component’s sizes.