Simple problems resolved

Good morning!

I added the files with the solutions.
They were created in Visual Studio 2010.

Here is a print screen of the VS Solution if you want to reproduce it:
![vs_solution](https://cloud.githubusercontent.com/assets/8064846/3478786/0748603c-0344-11e4-9cd8-14a79bd121ac.png)

The UnitTests project needs a reference to the SimpleProblems project.

Thank you for your time.
@cristi-badila 

I want to correct my answer. 
I did some tests and the function Math.Abs() is necessary.

To be sure if a number is duplicated, only the case when "jumping" to a position from the array, using the current iterated value, is accurate. 

But there is the case when, before finding any duplicates, the iteration gets to a position where the value has been changed to negative.
In this case that value is negative and needs to be changed to a proper index.

Also, because of this case changing the value to -1 will mess up the iteration. The "jump" won't be accurate.

@balauru 

I also want to correct my answer to you. I think its necessary to not alter the values of the array, only "mark" them when a "jump" has been made.