title: Build Binary Expression Tree
body: <p>Could someone explain how to build a binary expression tree.</p>
  
  <p>For example I have a string <code>2*(1+(2*1));</code> How to convert this into a binary expression tree.</p>
  
  <pre><code> *
   | \
   |  \
   2  +
      |\
      1 *
        |\
        2 1
  </code></pre>