title: How do I identify O(nlogn) exactly?
body: <p>I have understood O(logn) in a sense that it increases quickly but with larger inputs, the rate of increase retards. 
  I am not able to completely understand </p>
  
  <ol>
  <li><p>O(nlogn) </p></li>
  <li><p>the difference between an algorithm with complexity nlogn and complexity n + logn. </p></li>
  </ol>
  
  <p>I could use a modification of the phone book example and/or some basic python code to understand the two queries</p>