title: Any sites/books/tricks to practice recursion and OO design?
body: <p>I just wanted to know if there are any sites which have problems for practicing recursion and OO design(given a few entities designing the class/interface structure)?</p>
  
  <p>I understand the solutions to problems needing recursion without any difficulties but I can't seem to apply recursion to a new problem.Are there any tricks to apply recursion? I apologize if this question is very dumb!</p>