Advent of Code F# – Day 23

You can become a serverless blackbelt. Enrol to my 4-week online workshop Production-Ready Serverless and gain hands-on experience building something from scratch using serverless technologies. At the end of the workshop, you should have a broader view of the challenges you will face as your serverless architecture matures and expands. You should also have a firm grasp on when serverless is a good fit for your system as well as common pitfalls you need to avoid. Sign up now and get 15% discount with the code yanprs15!

ps. look out for all my other solutions for Advent of Code challenges here.

 

Day 23

See details of the challenge here.

Today’s input looks like this:

cpy a b
dec b
cpy a d
cpy 0 a
cpy b c
inc a

..

Today’s challenge is an extension to Day 12, where we have introduced a new instruction for toggle (tgl). To make toggling logic simpler let’s introduce a union type to represent the different instructions we can receive and write a function parse them.

Next, let’s add a toggle function to toggle a given instruction and modify the execute function from Day 12 to work with the union type and support the new tgl instruction as well.

Now we can solve part 1.

let part1 = (execute [ “a”, 7 ] inputs).[“a”]

 

Part 2

The safe doesn’t open, but it does make several angry noises to express its frustration.

You’re quite sure your logic is working correctly, so the only other thing is… you check the painting again. As it turns out, colored eggs are still eggs. Now you count 12.

As you run the program with this new input, the prototype computer begins to overheat. You wonder what’s taking so long, and whether the lack of any instruction more powerful than “add one” has anything to do with it. Don’t bunnies usually multiply?

Anyway, what value should actually be sent to the safe?

As the description eludes to, if we use 12 as initial input it might take a while to run.. and the naive approach of just executing the logic as before, ie

let part2 = (execute [ “a”, 12 ] inputs).[“a”]

took a good 4 minutes to run on my 2015 MBP.

If you add a few printfn statements and you’ll a few blocks of instructions that repeat for many cycles, eg.

cpy b c
inc a
dec c
jnz c -2
dec d
jnz d -5

you can add a short-circuit when you see this happen and replace it with the equivalent of a = b * d (as the description eluded to).

 

Links

Liked this article? Support me on Patreon and get direct help from me via a private Slack channel or 1-2-1 mentoring.
Subscribe to my newsletter


Hi, I’m Yan. I’m an AWS Serverless Hero and I help companies go faster for less by adopting serverless technologies successfully.

Are you struggling with serverless or need guidance on best practices? Do you want someone to review your architecture and help you avoid costly mistakes down the line? Whatever the case, I’m here to help.

Hire me.


Skill up your serverless game with this hands-on workshop.

My 4-week Production-Ready Serverless online workshop is back!

This course takes you through building a production-ready serverless web application from testing, deployment, security, all the way through to observability. The motivation for this course is to give you hands-on experience building something with serverless technologies while giving you a broader view of the challenges you will face as the architecture matures and expands.

We will start at the basics and give you a firm introduction to Lambda and all the relevant concepts and service features (including the latest announcements in 2020). And then gradually ramping up and cover a wide array of topics such as API security, testing strategies, CI/CD, secret management, and operational best practices for monitoring and troubleshooting.

If you enrol now you can also get 15% OFF with the promo code “yanprs15”.

Enrol now and SAVE 15%.


Check out my new podcast Real-World Serverless where I talk with engineers who are building amazing things with serverless technologies and discuss the real-world use cases and challenges they face. If you’re interested in what people are actually doing with serverless and what it’s really like to be working with serverless day-to-day, then this is the podcast for you.


Check out my new course, Learn you some Lambda best practice for great good! In this course, you will learn best practices for working with AWS Lambda in terms of performance, cost, security, scalability, resilience and observability. We will also cover latest features from re:Invent 2019 such as Provisioned Concurrency and Lambda Destinations. Enrol now and start learning!


Check out my video course, Complete Guide to AWS Step Functions. In this course, we’ll cover everything you need to know to use AWS Step Functions service effectively. There is something for everyone from beginners to more advanced users looking for design patterns and best practices. Enrol now and start learning!


1 thought on “Advent of Code F# – Day 23”

  1. Pingback: Advent of Code F# – Day 25 | theburningmonk.com

Comments are closed.