title: Unique Combinations of Digits in C
body: <p>I need to design an algorithm in C to calculate unique combinations of digits for 0 to 1,000,000. For example, when 13 appears, 31 would not be included in this sequence. Can anyone help me find an algorithm to describe this? The first few numbers in the series would be:</p>
  
  <pre><code> 1,2,3,4,5,6,7,8,9,11,12,13,14,15,16,17,18,19,22,23,24,25,26,27,28,29,33,etc
  </code></pre>
  
  <p>Thanks!</p>
  
  <p>edit - Sorry, forgot to mention that zero isn't included </p>