title: Find full path of a file in a file system
body: <p>I have a file system like this:</p>
  
  <pre><code>C Drive - Docements - (empty)
          - Music - Rock - a.mp3
                  - Jazz - SmoothJazz - b.mp3
          - Photo - (empty)
  D Drive - (empty)
  </code></pre>
  
  <p>Every file or directory has an id, and its parent's id. Now given a file name or directory name, how do you find the full path of it?</p>
  
  <p>My algorithm is:</p>
  
  <pre><code>Recursively (
      if (parent id is not null)
          find parent id in the table
  )
  </code></pre>