title: Difference between BFS and DFS
body: <p>I am reading about <code>DFS</code> in <em>Introduction to Algorithms</em> by Cormen. Following is text 
  snippet.</p>
  
  <blockquote>
    <p>Unlike BFS, whose predecessor subgraph forms a tree, the predecessor
    subgrpah produced by DFS may be composed of several trees, because
    search may be repeated from multiple sources. </p>
  </blockquote>
  
  <p>In addition to above notes, following is mentioned.</p>
  
  <blockquote>
    <p>It may seem arbitrary that BFS is limited to only one source where as
    DFS may search from multiple sources. Although conceptually, BFS
    could proceed from mutilple sources and DFS could limited to one
    source, our approach reflects how the results of these searches are
    typically used.</p>
  </blockquote>
  
  <p>My question is</p>
  
  <ol>
  <li>Can any one give an example how BFS is used with multiple source and
  DFS is used with single source?</li>
  </ol>