Chapter 2: Getting Started

@laurocaetano, @rmascarenhas, @andrielfn and @rcillo After a lot of effort on this chapter I tried my best to solve exercises and problems, but couldn't finish all of them.
but the inversion wasn't supposed to be the index positions of each element in the array? the inversion is the pair of `(i, j)` where `i < j`. Or am I missing something?