title: Create unique pair based on the giving array
body: <p>I was unable to solve this question. Looking for the help of algo expert.
  It will be great if the solution is provided in javascript, but it does not matter.</p>
  <p>Given input:</p>
  <pre><code>[
   [1,2,3]
   [4,5,6]
   [7,8]
   ...
  ]
  </code></pre>
  <p>Expected output:</p>
  <pre><code>[
   [1,4,7]
   [1,4,8]
   [1,5,7]
   [1,5,8]
   [1,6,7]
   [1,6,8]
   [2,4,7]
   [2,4,8]
   [2,5,7]
   [2,5,8]
   [2,6,7]
   [2,6,8]
   [3,4,7]
   [3,4,8]
   [3,5,7]
   [3,5,8]
   [3,6,7]
   [3,6,8]
  ] 
  </code></pre>