title: trying to understand string permutations?
body: <p>I found this sweet code here:
  <a href="http://geeksforgeeks.org/?p=767" rel="nofollow">http://geeksforgeeks.org/?p=767</a>
  the source link: <a href="http://mathworld.wolfram.com/Permutation.html" rel="nofollow">http://mathworld.wolfram.com/Permutation.html</a></p>
  
  <p>ok how do I even begin to understand these codes?
  how do I start coding like this?
  I have encountered many such codes...using dynamic programming, backtracking, branch and bound...and understood squat.</p>
  
  <p>even if u debug them..u cannot understand much..let alone start coding like them.</p>
  
  <p>is some kind of advanced math knowledge is needed..?</p>