#2 - Getting Started

Hey guys /cc @andrielfn, @laurocaetano, @fabioyamate, @rcillo

I'm pushing my stuff related to Chapter 2. Please note that the closer I got to the end, the poorer the quality got, since I got tired and entered :horse: mode. Please review what you can :smile: 

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## Exercises

![exercises1](https://cloud.githubusercontent.com/assets/613784/3639591/416e0258-1082-11e4-8abf-3daaf6ad90dc.png)
![exercises2](https://cloud.githubusercontent.com/assets/613784/3639593/49ca5b90-1082-11e4-84be-d38971948a1a.png)
![exercises3](https://cloud.githubusercontent.com/assets/613784/3639596/5468d4dc-1082-11e4-9c7c-80acca9c3667.png)

## Problems

![problems1](https://cloud.githubusercontent.com/assets/613784/3639597/5a880446-1082-11e4-8d6c-a3e6d6dca447.png)
![problems2](https://cloud.githubusercontent.com/assets/613784/3639598/60a12d26-1082-11e4-8d06-618fde319d88.png)
![problems3](https://cloud.githubusercontent.com/assets/613784/3639600/641d2892-1082-11e4-849e-fb32443dadb1.png)
![problems4](https://cloud.githubusercontent.com/assets/613784/3639614/af977b9c-1082-11e4-932e-9a1a92e791f5.png)
![problems5](https://cloud.githubusercontent.com/assets/613784/3639615/b326b1c4-1082-11e4-89f5-9096cd013715.png)

I believe this invariant would also be right, and even that it is equivalent to mine.

Saying that `v` can only be at index `j`, is the same as saying that `v` is not in the remaining positions. I think it's just a different way to express the same idea.