# Haskell Quiz/PP Pascal/Solution Kelan

### From HaskellWiki

Pretty basic solution. Find the biggest number the triangle will contain given the number of rows, use that number to determine column widths. Then just print out each row with the correct columns and spacing.

import System.Environment nCr n r = ( product [ ( s + 1 ) .. n ] ) `div` ( product [ 2 .. t ] ) where s = max r ( n - r ) t = min r ( n - r ) -- maximum number in a pascal triangle -- with given number of rows trimax rows = nCr ( rows - 1 ) ( ( rows - 1 ) `div` 2 ) main = do args <- getArgs let rows = read . head $ args digits = 1 + ( truncate . logBase 10 . fromIntegral . trimax $ rows ) pad s = ( replicate ( digits - length s ) ' ' ) ++ s for_ = flip mapM_ for_ [ 0 .. ( rows - 1 ) ] $ \ n -> do putStr . concat . replicate ( rows - n - 1 ) . pad $ "" for_ [ 0 .. n ] $ \ r -> do putStr . pad . show . nCr n $ r putStr . pad $ "" putStrLn ""