title: In a tree data structure, display tree nodes level by level
body: <p><strong>Question:</strong> how can we display tree nodes  level by level ?. could you please give me time and space efficient solution .</p>
  
  <p><strong>Example :</strong></p>
  
  <pre><code>    A
     / \
    B   C
   / \  / \
  D   E F  G
  
  void PrintTree(struct tree *root);
  </code></pre>
  
  <p><strong>Output:</strong>
  You have to print tree nodes level by level</p>
  
  <pre><code>  A
    B C
    D E F G
  </code></pre>