title: Remove Blank spaces in a string in O(n)
body: <p>How to remove blank spaces in a string with a complexity of O(n). 
  My approach is using two indexes. One will traverse till length on string. Other will be incremented only when a non-blank character is encountered.
  But i am not sure of this approach.</p>
  
  <p>TIA,
  Praveen</p>