title: How to calculate specific cards combination index
body: <p>There are 22100 combinations of 3 cards from the 52 cards deck <code>(52 * 51 * 50 / 3! = 22100)</code>.</p>
  
  <p>Here is an enumeration of all these combinations:</p>
  
  <pre><code>    static const ins cards_count = 52;
      int boardId = 0;
  
      for (int b1 = 0; b1 &lt; card_count; b1++)
      { 
          for (int b2 = b1 + 1; b2 &lt; card_count; b2++)
          {
              for (int b3 = b2 + 1; b3 &lt; card_count; b3++)
              {
                 cout &lt;&lt; boardId &lt;&lt; endl;
                 boardId++;
              }
          }
      }
  </code></pre>
  
  <p>Is it posssible to write an indexer fucntion that converts b1, b2, b3 to the boardId (without using a map)? If this is hard maybe you can advise some hash fucntion that maps b1, b2, b3 to the int size hash.</p>