Practice Coding Challenge: Dubstep Decoder - Why I Chose To Learn About Software Engineering

Intro

If you read my blog a couple weeks ago or the one from last week, you’ll know that I’m currently working on building upon my Vanilla JavaScript foundation with lessons and coding challenges. Sometimes this looks like researching different JS methods I may be less familiar with, and sometimes it may be me working through some challenges on HackerRank, Codewars, etc. I’ve found that the difficulty of the challenges (for me, at least) doesn’t always match up with the reward system for each site, so I like to bounce around to different levels to see what I can do. I liked this challenge enough to post about it today, because a) I thought it used pretty practical skills to have brushed up on as a programmer, and b) I thought the story scenario was pretty fun/funny.

The Problem

You can find this challenge here if you’re interested in solving it for yourself before seeing how I did it. I recommend it! It’s a relatively short challenge overall. Okay, here’s the scenario from Codewars:

Polycarpus works as a DJ in the best Berland nightclub, and he often uses dubstep music in his performance. Recently, >he has decided to take a couple of old songs and make dubstep remixes from them.

Let’s assume that a song consists of some number of words (that don’t contain WUB). To make the dubstep remix of this >song, Polycarpus inserts a certain number of words “WUB” before the first word of the song (the number may be zero), >after the last word (the number may be zero), and between words (at least one between any pair of neighbouring words), >and then the boy glues together all the words, including “WUB”, in one string and plays the song at the club.

For example, a song with words “I AM X” can transform into a dubstep remix as “WUBWUBIWUBAMWUBWUBX” and >cannot transform into “WUBWUBIAMWUBX”.

Recently, Jonny has heard Polycarpus’s new dubstep track, but since he isn’t into modern music, he decided to find out >what was the initial song that Polycarpus remixed. Help Jonny restore the original song.

Input The input consists of a single non-empty string, consisting only of uppercase English letters, the string’s length doesn’t >exceed 200 characters

Output Return the words of the initial song that Polycarpus used to make a dubsteb remix. Separate the words with a space.

Examples songDecoder(“WUBWEWUBAREWUBWUBTHEWUBCHAMPIONSWUBMYWUBFRIENDWUB”) // => WE ARE THE CHAMPIONS MY FRIEND

Plan of Action

To be honest, I had to read through this description 3 times to get a good understanding of what it’s asking me to do. Here is ultimately what it’s asking us to find: Remove the “WUB” from the song lyrics given, but maintain spaces between words in the lyrics. My pseudocode version of the solution looks like:

songDecoder(songLyrics) {
    replace "WUB" with " "
}

My Solution

In the end, my actual code didn’t look much different from the pseudocode (hence a good reason to start there!) My thought process went like this:

Split the string at the “WUB” into an array
Remove the empty strings from the array

Join the words from the array to a new string of song lyrics

function songDecoder(songLyrics) {
 return (
     songLyrics
         .split("WUB") //Step 1: Split the string at the "WUB" into an array
         .filter(Boolean) // Step 2: Remove the empty strings from the array
         .join(" ") //Step 3: Join the words from the array to a new string of song lyrics
 )
}

Overall, this solution is mostly pretty straight forward. The new thing I learned with this was that .filter(Boolean) step. I’ll try my best to explain my understanding of it, but definitely check out this post on Devign.me for a very thorough explaination (like I did.) An addition in ES5, the filter method here removes all falsy values (false, null, undefined, 0, NaN, and empty string) from an array. I used this to remove the empty strings from my array of split words, which then let us join them together with a space in between.

Conclusion

Like I said in the beginning, this is a relatively straight forward challenge. Ultimately, the difficulty comes down to deciphering what all the words are really asking you to do. Had I used Google, I would’ve found an even more straight forward answer of song.replace(/(WUB)+/g, " ").trim() before thinking through the challenge step by step the way I did above. Thanks again for reading! I plan on continuing this theme of alternating writing a coding challenge I’ve worked through with what JavaScript topic I’m currently working on, so be on the lookout for that later.