title: Creating random numbers with no duplicates
body: <p>In this case, the MAX is only 5, so I could check the duplicates one by one, but how could I do this in a simpler way? For example, what if the MAX has a value of 20?
  Thanks.</p>
  
  <pre><code>int MAX = 5;
  
  for (i = 1 , i &lt;= MAX; i++)
  {
          drawNum[1] = (int)(Math.random()*MAX)+1;
  
          while (drawNum[2] == drawNum[1])
          {
               drawNum[2] = (int)(Math.random()*MAX)+1;
          }
          while ((drawNum[3] == drawNum[1]) || (drawNum[3] == drawNum[2]) )
          {
               drawNum[3] = (int)(Math.random()*MAX)+1;
          }
          while ((drawNum[4] == drawNum[1]) || (drawNum[4] == drawNum[2]) || (drawNum[4] == drawNum[3]) )
          {
               drawNum[4] = (int)(Math.random()*MAX)+1;
          }
          while ((drawNum[5] == drawNum[1]) ||
                 (drawNum[5] == drawNum[2]) ||
                 (drawNum[5] == drawNum[3]) ||
                 (drawNum[5] == drawNum[4]) )
          {
               drawNum[5] = (int)(Math.random()*MAX)+1;
          }
  
  }
  </code></pre>