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#
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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
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