title: Performance of doing bitwise operations on bitsets
body: <p>In C++ if I do a logical OR (or AND) on two bitsets, for example:</p>
  
  <pre><code>bitset&lt;1000000&gt; b1, b2;
  //some stuff
  b1 |= b2;
  </code></pre>
  
  <p>Does this happen in O(n) or O(1) time? Why?</p>
  
  <p>Also, can this be accomplished using an array of bools in O(1) time?</p>
  
  <p>Thanks.</p>