title: Valid Permutation of Parenthesis
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/727707/solution-to-a-recursive-problem-code-kata">Solution to a recursive problem (code kata)</a>  </p>
  </blockquote>
  
  
  
  <p>give an algorithm to find all valid permutation of parenthesis for given n
  for eg :</p>
  
  <pre><code>for n=3, O/P should be
  {}{}{} 
  {{{}}}
  {{}}{} 
  {}{{}} 
  {{}{}}
  </code></pre>