title: When will Floyd's cycle-finding algorithm fail?
body: <p>I get an interview question about the <a href="http://en.wikipedia.org/wiki/Cycle_detection#Tortoise_and_hare" rel="nofollow">Floyd's cycle-finding algorithm</a> :</p>
  
  <p><strong>When will Floyd's cycle-finding algorithm fail ?</strong></p>
  
  <p>I mean, is there rule for finding the step between the fast and slow pointers ?</p>