title: Count Unique values with a condition
body: <p>In column A I have list of different names. In column B, I have values either 0 or 1.</p>
  
  <p><strong>I want to get a count of all the unique names from column A which have 1 in column B.</strong></p>
  
  <p>Using below array formula I am able count unique names but not able to apply condition on column B.</p>
  
  <pre><code>=SUM(1/COUNTIF(A:A,A:A))
  </code></pre>