title: Algorithm for detecting a double gutter in poker
body: <p>A double gutter in poker is when you have 2 gut shots to a straight.</p>
  
  <p>For example, if the board is 268 and you have 45, a 3 (23456) or a 7 (45678) will complete a straight for you.</p>
  
  <p>Given board[] and hand[], what's an efficient algorithm for returning true if you have a double gutter and false if not?</p>