title: linked list loop - cycle start element and list length
body: <p>I read about <a href="https://stackoverflow.com/questions/2663115/interview-question-how-to-detect-a-loop-in-a-linked-list">loop in linked list detection algorithm</a>
  and I doubt</p>
  
  <p>1) How to detect the <em>"meeting element"</em>. For example, in the follow case - how to detect that the <em>meeting</em> is at the 3nd element?</p>
  
  <p><img src="https://i.stack.imgur.com/tHZfA.jpg" alt="enter image description here"> </p>
  
  <p>2) How to detect the list's length (in case above - 6)</p>
  
  <p>Both questions in <strong>running time O(n) , memory O(1)</strong>.</p>