title: Upper bound vs lower bound for worst case running time of an algorithm
body: <p>I am learning about analysis of algorithms. I understand the concept of the <em>worst case running time</em> of an algorithm. </p>
  
  <p>However, what are upper and lower bounds on the worst case running time of an algorithm?</p>
  
  <p>What can be an example where an <em>upper bound</em> for the worst case running time of an algorithm is different from the <em>lower bound</em> for the worst case running time of the same algorithm?</p>