Math and PHP to find and print permutation sets : <p>I have a quiz of 6 questions that must be answered either yes (y) or no (n). So the set of answers might be</p>

<blockquote>
  <p>yynynn</p>
</blockquote>

<p>For another quiz of 6 questions the answers might be</p>

<blockquote>
  <p>nnnynn</p>
</blockquote>

<p>For another,</p>

<blockquote>
  <p>ynynyn</p>
</blockquote>

<p>I need a script to find and print the unique permutations of answer sets.</p>
