Best Ruby coding practices: https://github.com/uohzxela/clean-code-ruby

Using Ruby in 2019: https://jasoncharnes.com/using-ruby-in-2019/

Refactoring tips: https://github.com/ryanmcdermott/3rs-of-software-architecture

Interviews

5 Common Problems to solve: https://www.youtube.com/watch?v=GBuHSRDGZBY

What is Time Complexity? https://stackoverflow.com/questions/25824842/what-is-the-time-complexity-of-the-code

Tests

Hackerrank: https://www.hackerrank.com/domains/ruby

Daily Coding Problem: https://www.dailycodingproblem.com