title: Array remove duplicate elements
body: <p>I have an unsorted array, what is the best method to remove all the duplicates of an element if present?</p>
  
  <p>e.g:</p>
  
  <pre><code>a[1,5,2,6,8,9,1,1,10,3,2,4,1,3,11,3]
  </code></pre>
  
  <p>so after that operation the array should look like</p>
  
  <pre><code> a[1,5,2,6,8,9,10,3,4,11]
  </code></pre>