title: Intersection of two sets in most optimized way
body: <p>Given two sets of values, I have to find whether there is any common element among them or not i.e. whether their intersection is null or not.</p>
  
  <p>Which of the standard C# collection will suit best (in terms of performance) for this purpose? I know that <code>linq</code> has a <code>Intersect</code> extension method to find out the intersection of two list/arrays but my focus is on performance in terms of <code>Big-O notation</code>.</p>
  
  <p>And what if I have to find out the intersection of two sets as well? </p>