-- Find the maximum total from top to bottom of the triangle below:
import Data.List

triangle =
  [               [ 75 ]
  ,              [ 95,64 ]
  ,             [ 17,47,82 ]
  ,            [ 18,35,87,10 ]
  ,           [ 20,04,82,47,65 ]
  ,          [ 19,01,23,75,03,34 ]
  ,         [ 88,02,77,73,07,63,67 ]
  ,        [ 99,65,04,28,06,16,70,92 ]
  ,       [ 41,41,26,56,83,40,80,70,33 ]
  ,      [ 41,48,72,33,47,32,37,16,94,29 ]
  ,     [ 53,71,44,65,25,43,91,52,97,51,14 ]
  ,    [ 70,11,33,28,77,73,17,78,39,68,17,57 ]
  ,   [ 91,71,52,38,17,14,91,43,58,50,27,29,48 ]
  ,  [ 63,66,04,68,89,53,67,30,73,16,69,87,40,31 ]
  , [ 04,62,98,27,23,09,70,98,73,93,38,53,60,04,23 ]
  ]

maxLR xs = zipWith max xs (tail xs)
routes   = head . foldr1 (\xs ys -> zipWith (+) xs $ maxLR ys)
main     = print $ routes triangle