title: Variable size bitset
body: <p>I am practicing a question on array in which I have to find unique elements. Now for this my logic is to find the max element in the array and define the bitset for that. But problem is bitset needs a constant value so how to overcome this, below are some of my question on this:</p>
  
  <p>a) Can I, by any chance, define the bitset with a variable size?<br>
  b) If not, then what is the best approach to use <code>vector&lt;bool&gt;</code> or <code>vector&lt;char&gt;</code>?<br>
  c) I know boost has a dynamic bitset but as I am doing this for learning I want to know of alternate approaches.</p>