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Thumbnail for Day 3 (Advent of Code 2022)

Day 3 (Advent of Code 2022)

Part 1

I’m not sure where the day 3 challenge is going, because the problem statement for the first part is kinda convoluted.

As usual we have an input, like this:

vJrwpWtwJgWrhcsFMMfFFhFp jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL PmmdzqPrVvPwwTWBwg wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn ttgJtRGJQctTZtZT CrZsJsPPZsGzwwsLwLmpwMDw

Each line represents the contents of a “rucksack”, divided in two halves (which are called “compartments”), so for line 1:

Thumbnail for Day 15 (Advent of Code 2022)

Day 15 (Advent of Code 2022)

The day 15 puzzle falls into the “math puzzle” territory more than “let’s learn something new about Rust”, but since several folks asked if I was going to continue… let’s continue.

The sample input is as follows:

Sensor at x=2, y=18: closest beacon is at x=-2, y=15 Sensor at x=9, y=16: closest beacon is at x=10, y=16 Sensor at x=13, y=2: closest beacon is at x=15, y=3 Sensor at x=12, y=14: closest beacon is at x=10, y=16 Sensor at x=10, y=20: closest beacon is at x=10, y=16 Sensor at x=14, y=17: closest beacon is at x=10, y=16 Sensor at x=8, y=7: closest beacon is at x=2, y=10 Sensor at x=2, y=0: closest beacon is at x=2, y=10 Sensor at x=0, y=11: closest beacon is at x=2, y=10 Sensor at x=20, y=14: closest beacon is at x=25, y=17 Sensor at x=17, y=20: closest beacon is at x=21, y=22 Sensor at x=16, y=7: closest beacon is at x=15, y=3 Sensor at x=14, y=3: closest beacon is at x=15, y=3 Sensor at x=20, y=1: closest beacon is at x=15, y=3
Thumbnail for Dynamic symbol resolution

Dynamic symbol resolution

Let’s pick up where we left off: we had just taught elk to load not only an executable, but also its dependencies, and then their dependencies as well.

We discovered that ld-linux walked the dependency graph breadth-first, and so we did that too. Of course, it’s a little bit overkill since we only have one dependency, but, nevertheless, elk happily loads our executable and its one dependency:

Lies we tell ourselves to keep using Golang

In the two years since I’ve posted I want off Mr Golang’s Wild Ride, it’s made the rounds time and time again, on Reddit, on Lobste.rs, on HackerNews, and elsewhere.

And every time, it elicits the same responses:

  • You talk about Windows: that’s not what Go is good at! (Also, who cares?)
  • This is very one-sided: you’re not talking about the good sides of Go!
Thumbnail for Day 9 (Advent of Code 2020)

Day 9 (Advent of Code 2020)

Day 9’s problem statement is convoluted - the “ah maybe that’s why I don’t usually do Advent of Code” kind of convoluted, but let’s give it a go anyway.

So, we have a series of numbers, like so:

35 20 15 25 47 40 62 55 65 95 102 117 150 182 127 219 299 277 309 576

And uh the first N numbers are a “preamble” and every number that comes after that must be the sum of any two of the numbers that come before it.

Thumbnail for Building a Rust service with Nix

Building a Rust service with Nix

I often give bits and pieces of advice on how to build Rust stuff the comfy way. But it can be hard to see how everything comes together, especially when it comes to, say, deploying a web service in production.

So, let’s start from the very beginning (setting up a Linux VM), and march together towards the objective: a production-grade Rust web service, built with Nix.

The shortest ooc quine

A few days ago I posted an ooc quine. But while browing HackerNews, I found an even shorter one. The shortest!

Here it is, in its full glory

Can’t see anything? That’s an empty file. It will compile and run just fine. ooc doesn’t require a main function - you can just shove code in there that will run at the program’s initialization. If there’s none, no big deal! It’ll just not run anything.

Thumbnail for Thread-local storage

Thread-local storage

Welcome back and thanks for joining us for the reads notes… the thirteenth installment of our series on ELF files, what they are, what they can do, what does the dynamic linker do to them, and how can we do it ourselves.

I’ve been pretty successfully avoiding talking about TLS so far (no, not that one) but I guess we’ve reached a point where it cannot be delayed any further, so.

Thumbnail for Day 6 (Advent of Code 2022)

Day 6 (Advent of Code 2022)

Today I am joining you from the relative discomfort of my living room (since my better half has commandeered the home office due to Way Too Many Calls) to tackle the day 6 challenge, which I’m excited about: maybe despite, maybe because of, the low-grade fever I’m under.

Part 1

Our input is a jumble of letters, and we’re supposed to find the position of the first substring that’s “four different characters”.

Working with strings in Rust

There’s a question that always comes up when people pick up the Rust programming language: why are there two string types? Why is there String, and &str?

My Declarative Memory Management article answers the question partially, but there is a lot more to say about it, so let’s run a few experiments and see if we can conjure up a thorough defense of Rust’s approach over, say, C’s.