My solutions may not be the most elegant or efficient, but they are the results of my own mental labor.
I've solved all the algorithm challenges (16 basic, 21 intermediate, 5 advanced) in freeCodeCamp's JavaScript Algorithms and Data Structures curriculum and achieved a freeCodeCamp Algorithms certificate, which represents an estimated 300 hours of coursework. My solutions used to be visible in my freeCodeCamp profile, but freeCodeCamp no longer stores user solutions after its major update in 2018. I still have my solutions stored locally, so I plan on transferring them here.
I've finally leveled up to 5 kyu in CodeWars! Kyu is a term borrowed from Go, a Chinese board game, and indicates the number of degrees away from master level (dan). Beginners start at 8 kyu. You can view my complete collection of solutions on my CodeWars profile.
I'm getting my feet wet in technical interview style algorithm challenges by solving easy problems in CodeSignal's interview practice section.
Also working through Leetcode's Top Interview Questions, the easy collection.
I'm also dabbling in solving challenges in Hackerrank's Interview Preparation Kit.
I'm practicing for technical interviews by pair programming on Pramp. Practice makes perfect!