title: Time complexity of unordered_set<int> find method
body: <p>What is the time complexity of <a href="http://www.cplusplus.com/reference/unordered_map/unordered_map/find/" rel="noreferrer">find</a> method in <code>unordered_set&lt;int&gt;</code>?</p>
  
  <p>And also is it possible to change the hash functions ?</p>