title: Dijkstra Algorithm Time Complexity
body: <p>I am new to Dijkstra Algorithm.</p>
  <p>My question is that: for an undirected graph G with n nodes and m edges, the time complexity for Dijkstra Algorithm to find shortestst path is o((n+m)logn). However, if the G is connected, why this time complexity can be also expressed as o(mlogn)?</p>
  <p>Cheers</p>