Practicing coding, especially algorithms, is a strong way to build up your abilities and prepare for a coding interview. These sites provide challenges for any level of coder.
Focus on diversity. The goal is wide coverage, not extended knowledge in one area. You can’t know for sure what question you’ll get in an interview. If you happen to get one you know, then great, otherwise you’ll rely on this practice to find a solution. Algorithms are rarely unique, and you can draw from your current knowledge to solve them.
Even if you’re coding is solid, doing some practice before an interview can calm your nerves. It’ll shift you to a stronger mindset, one ready to tackle algorithms, regardless of how silly they might be.
- CodinGame: A good assortment of games and AI challenges. Includes head-to-head speed competitions if you’re looking to train your nerves.
- codewars: A collection of challenges over many ranks and ranks. Lots of stats to pique your competitive spirit.
- coderbyte: A straight forward collection of challenges without much overhead or gamification.
This is not intended to be a complete list, but represents a good variety in styles.