Description taken straight from HackerRank:
30 Days of Code is an opportunity for you to learn how to code or brush up on your fundamentals. Each day, you'll unlock a new challenge and a corresponding video tutorial to help you learn.
The tutorial is Java-based, but you can also choose other popular languages to submit your solution. Topics include if-else statements, recursion, data structures and more.
I will be attempting to update this daily with my next answer to each days challenge. I do not own the rights to any of the problems in each folders README.md. To the best of my knowledge it is all property of HackerRank.