title: How to insert a array into unordered set?
body: <p>I want to create a tuple/array like <code>(0,1,2), (3,4,5)</code>. I want to store it into an <code>unordered_set</code>. But <code>unordered_set</code> didn't offer such a hash function. Can anyone tell me how can I do this?</p>
  
  <p>I have read thes answer:
  <a href="https://stackoverflow.com/questions/8026890/c-how-to-insert-array-into-hash-set">C++ how to insert array into hash set?</a> 
  but I don't want to add any extra code like hash function.</p>