A problem that has shown up multiple times in my preparation for technical interviews is the so called Ransom Note problem.
To solve this in F# is pretty simple.
In the interest of efficiency I decided to use a mutable Dictionary instead of the F# Map to store the no. of times a letter appears in the ransom note.
There’s also an optimization here to stop iterating through the magazine once all the letters for the ransom note is accounted for. One way to do it is to use Seq.takeWhile and mutate the Dictionary as we iterate through letters in the magazine, and stop when letters.Count = 0.
Try it Yourself
- A Java implementation
- Interview question on CareerCup
- DotNetFiddle snippet
- All my Project Euler solutions in F#
- All my Advent of Code solutions in F#
I specialise in rapidly transitioning teams to serverless and building production-ready services on AWS.
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.
Check out my new 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. Including basic concepts, HTTP and event triggers, activities, callbacks, nested workflows, 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