Learn By Doing #1

Duplicate client ID

You've been given a csv file containing lots of serial numbers and client IDs for futuristic IoT devices. Unfortunately there's a duplicate client ID in the csv file, which will cause issues when the entries are inserted into a database.

Using your prefered programming language, find the two serial numbers associated with the duplicated client ID. Your solution should focus on efficiency.

Good luck!

Running

Use hyperfine

Added sbt-assembly

then sbt assembly creates a jar

hyperfine "java -jar target/scala-2.13/Learn\ By\ Doing\ Number\ 1-assembly-0.1.0-SNAPSHOT.jar"

Solutions

Attempt 1

Duration: ~17 seconds 5 seconds is the parsing the csv file into a list...

Import csv file as text. Turn into List Filter list -> check every item to see if it shares a duplicate client id

Attempt 2

Duration: ~ 10 seconds 5 seconds is the parsing the csv file into a list...

Import csv file as text Turn into List Find first -> check every item to see if it shares a duplicate client id

Need to ditch the double list operation

Attempt 3

Duration: ~ 5 seconds 5 seconds is the parsing the csv file into a list?

Import csv file as text Turn into List Group items by ClientId, find one with count of 2.

Can we speed up the parsing?

Attempt 4

Duration: ~300ms

Import csv file, immediately turn into list of arrays Group items by ClientId, find one with count of 2.