title: Maximum number of edges in unconnected graph
body: <p>In an undirected graph with <code>n</code> vertices and no edges, what is the maximum number of edges that can be added so that the graph remains unconnected? This is an interview question. </p>
  
  <ol>
  <li>NC2</li>
  <li>(N-1)C2</li>
  <li>N!</li>
  <li>(N-1)!</li>
  </ol>