title: Questions about calculating time complexity
body: <p><img src="https://i.stack.imgur.com/qLuie.png" alt=""></p>
  
  <p>I tried to solve this question and I know the answer should be O(n^2) and omega(n^2). But the solution for part b is a bit confusing. I don't know why we need to choose n/2 to calculate omega. Can someone kindly tell me the reason?</p>