title: What is a C++ data structure that offers O(1) lookup?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/133569/hashtable-in-c">Hashtable in C++?</a>  </p>
  </blockquote>
  
  
  
  <p>I was originally planning on using a C++ set for a hash-like data structure that offers O(1) lookup.</p>
  
  <p>However, I realized that the complexity for lookup in sets is actually O(logn):</p>
  
  <p><a href="http://www.cplusplus.com/reference/stl/set/find/" rel="nofollow noreferrer">http://www.cplusplus.com/reference/stl/set/find/</a></p>
  
  <p>Is there a data structure akin to a hash table in C++ that offers O(1) lookup?</p>