title: Pascals triangle advantages
body: <p>Pascal triangle can be used to calculate number of combinations using the recursion formula below:-</p>
  
  <pre><code>(n k) = (n-1 k-1) + (n-1 k)
  </code></pre>
  
  <p>This can be used in place of formal expansion of (n k) to calculate number of combinations.
  But both perform in O(n) time.What are the advantages of using Pascal's triangle method?</p>