title: Finding all possible combinations of numbers to reach a given sum
body: <p>How would you go about testing all possible combinations of additions from a given set <code>N</code> of numbers so they add up to a given final number?</p>
  
  <p>A brief example:</p>
  
  <ul>
  <li>Set of numbers to add: <code>N = {1,5,22,15,0,...}</code></li>
  <li>Desired result: <code>12345</code></li>
  </ul>