advent03.hs

   1 import Data.List (transpose, sort)
   2 import Data.List.Split (splitOn, chunksOf)
   3
   4 type Triple = [Integer]
   5
   6 main :: IO ()
   7 main = do
   8         instrText <- readFile "advent03.txt"
   9         let triangles = map (parseLine) $ lines instrText
  10         part1 triangles
  11         part2 triangles
  12
  13
  14 part1 :: [Triple] -> IO ()
  15 part1 triangles = do
  16     print $ length $ filter (validTriangle) triangles
  17
  18 part2 :: [Triple] -> IO ()
  19 part2 triangles = do
  20     print $ length $ filter (validTriangle) $ byColumns triangles
  21
  22
  23 parseLine :: String -> Triple
  24 parseLine = map (read) . filter (not . null) . splitOn " "
  25
  26 validTriangle :: Triple -> Bool
  27 validTriangle triple = sortedTriple!!0 + sortedTriple!!1 > sortedTriple!!2
  28     where sortedTriple = sort triple
  29
  30 byColumns :: [[Integer]] -> [Triple]
  31 byColumns = chunksOf 3 . concat . transpose