If you enjoy reading these exercises then please buy Crista’s book to support her work.
Style 7 – Infinite Mirror
This style is really all about recursions.
- All, or a significant part, of the problem is modelled using induction.
First, let’s get the list of stop words and put them in a set:
and then we will implement the counting logic using recursion:
I made some adjustments to Crista’s version here. In her version, wordFreqs is a global state that has been passed in as argument but the recursive count function returns nothing.
In my implementation, although I’m still using a mutable dictionary, it’s an implementation detail that is not exposed to the outside world. I could have used a Map here instead, but constantly updating a Map is really clumsy, plus Map performs really poorly in this type of use pattern.
Then we have another recursive functions, for printing out the word frequencies:
and then some code to tie everything together:
You can find all the source code for this exercise here.
Enjoy what you’re reading? Subscribe to my newsletter and get more content on AWS and serverless technologies delivered straight to your inbox.
I’m an AWS Serverless Hero and the author of Production-Ready Serverless. I have run production workload at scale in AWS for nearly 10 years and I have been an architect or principal engineer with a variety of industries ranging from banking, e-commerce, sports streaming to mobile gaming. I currently work as an independent consultant focused on AWS and serverless.
In this course, we’ll cover everything you need to know to use AWS Step Functions service effectively. Including basic concepts, HTTP and event triggers, activities, design patterns and best practices.
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.
- Lambda optimization tip – enable HTTP keep-alive
- You are thinking about serverless costs all wrong
- Many faced threats to Serverless security
- We can do better than percentile latencies
- I’m afraid you’re thinking about AWS Lambda cold starts all wrong
- Yubl’s road to Serverless
- AWS Lambda – should you have few monolithic functions or many single-purposed functions?
- AWS Lambda – compare coldstart time with different languages, memory and code sizes
- Guys, we’re doing pagination wrong