title: Optimal solution for the "celebrity" algorithm
body: <p>Among <code>n</code> persons,a "<em>celebrity</em>" is defined as someone
  <strong>who is known by everyone but does not know anyone</strong>. The
  problem is to identify the celebrity, if one exists, by asking the
  question only of the form, "<em>Excuse me, do you know the person
  over there?</em>" (The assumption is that all the answers are correct,
  and even that celebrity will also answer.) 
  The goal is to minimize the number of questions. </p>
  
  <p>Is there a solution of the order less than the obvious <code>O(n^2)</code> here?</p>