title: STL + Ordered set + without duplicates
body: <p>I need to have an ordered set of values without duplicates.
  So, what is the fast/best method :</p>
  
  <p>1 - Create a vector, sort it and remove duplicates ?
  2 - Use a kind of "sorted" vector (if it exists) ?</p>
  
  <p>Which one can be the more efficient ?</p>