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.
See details of the challenge here.
The input for today’s challenge looks like this:
rotate row y=0 by 10
rotate row y=0 by 10
rotate row y=0 by 5
rotate column x=43 by 1
rotate column x=40 by 2
rotate column x=38 by 1
So, our first task is to parse this input into something more workable (something like the Cmd union type we’ve declared below).
Notice that I used active patterns instead of plain functions:
- StartsWith returns the substring after the specified prefix
- SepBy returns the 2 numbers separated by either “x” or “by” (eg. “1×1”, “0 by 5”)
I find this style of parsing code easier to understand as it structurally matches the input line and mentally I don’t have to follow any branching logic.
Next, let’s model the screen and the different operations against it – rect, rotate row and rotate column.
Here I’ve gone with an imperative approach for efficiency sake, duplicating the 50×6 2D array repeatedly (at least once per command) just doesn’t sit well with me.
Anyhow, once we apply the commands parsed from the input file we need to count the no. of true elements in our 2D array to answer part 1.
You notice that the screen is only capable of displaying capital letters; in the
font it uses, each letter is 5 pixels wide and 6 tall.
After you swipe your card, what code is the screen trying to display?
To solve part 2, the easiest way I could think of was to print it out and see what letters are spelled out.
which in my case spelled out:
- Day 8 challenge description
- Advent of Code 2015
- Solution for Day 7
- All my F# solutions for Advent of Code
- Github repo
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.
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”.
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!
Here is a complete list of all my posts on serverless and AWS Lambda. In the meantime, here are a few of my most popular blog posts.
- All you need to know about caching for serverless applications
- Choreography vs Orchestration in the land of serverless
- Are Lambda-to-Lambda calls really so bad?
- Lambda optimization tip – enable HTTP keep-alive
- You are wrong about serverless and vendor lock-in
- You are thinking about serverless costs all wrong
- Check-list for going live with API Gateway and Lambda
- How to choose the right API Gateway auth method
- AWS Lambda – should you have few monolithic functions or many single-purposed functions?
- Guys, we’re doing pagination wrong
- Top 10 Serverless framework best practices
- I left full-time employment, here’s what happened since
- How to break the “senior engineer” career ceiling
- My advice to junior developers