Solve day 5 part 2

haskell/Puzzles/Day5.hs

@@ -1,9 +1,8 @@
 module Puzzles.Day5 (puzzle) where
 
 import Control.Monad
-import Data.Functor
-import Data.List.Extra
-import Data.Maybe
+import Data.List
+import Data.Ord
 import Data.Text.Lazy qualified as TL
 import Puzzle
 import Text.Megaparsec hiding (some)
@@ -25,6 +24,12 @@ puzzle =
                     . length
                     . filter (flip any ranges . isInRange)
                     $ vals
+            , TL.show
+                . sum
+                . map rangeLength
+                . foldr addInterval []
+                . sortOn (Down . (.lower))
+                . fst
             ]
         , extraTests = mempty
         }
@@ -35,5 +40,19 @@ data Range = Range
     }
     deriving (Eq, Ord, Show)
 
+rangeLength :: Range -> Int
+rangeLength r = r.upper - r.lower + 1
+
 isInRange :: Int -> Range -> Bool
 isInRange n r = n >= r.lower && n <= r.upper
+
+extend :: Int -> Range -> Range
+extend upper r = r{upper = max r.upper upper}
+
+addInterval :: Range -> [Range] -> [Range]
+addInterval new = \case
+    [] -> [new]
+    (r : rs) ->
+        if isInRange new.lower r
+            then extend new.upper r : rs
+            else new : r : rs

outputs/real/5/2

@@ -0,0 +1 @@
+348548952146313