### Concepts

#### Fork / Join

Fork/Join or Divide and Conquer is a very powerful abstraction to solve hierarchical problems. When talking about hierarchical problems, think about quick sort, merge sort, file system or general tree navigation and such.

- Fork / Join algorithms essentially split a problem at hands into several smaller sub-problems and recursively apply the same algorithm to each of the sub-problems.
- Once the sub-problem is small enough, it is solved directly.
- The solutions of all sub-problems are combined to solve their parent problem, which in turn helps solve its own parent problem.