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make sure that Matrix.groupWith sorts the values before grouping

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JasterV 2025-03-26 00:26:48 +01:00
parent ed7e95b59d
commit fda3ec56bc
1 changed files with 5 additions and 4 deletions
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9
src/Day4/Matrix.hs
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@ -14,8 +14,8 @@ where
import Data.HashMap.Lazy (HashMap) import Data.HashMap.Lazy (HashMap)
import qualified Data.HashMap.Lazy as HashMap import qualified Data.HashMap.Lazy as HashMap
import Data.IntMap.Lazy (IntMap)
import qualified Data.IntMap.Lazy as IntMap import qualified Data.IntMap.Lazy as IntMap
import Data.List (sortOn)
import Data.Maybe import Data.Maybe
import Prelude hiding (lookup) import Prelude hiding (lookup)
@ -48,12 +48,13 @@ lookupMultiple positions matrix = mapMaybe (`lookup` matrix) positions
{-- {--
Given a matrix of elements and a function mapping a position into an aggregation of its values, Given a matrix of elements and a function mapping a position into an aggregation of its values,
group the elements by the aggregation result group the elements by the aggregation result.
The values are grouped in order.
--} --}
groupWith :: forall v. ((Int, Int) -> Int) -> Matrix v -> [[v]] groupWith :: forall v. ((Int, Int) -> Int) -> Matrix v -> [[v]]
groupWith f (Matrix hmap) = groupWith f (Matrix hmap) =
let intMap :: IntMap [v] let sortedEntries = sortOn fst $ HashMap.toList hmap
intMap = HashMap.foldrWithKey (insertValue . f) IntMap.empty hmap intMap = foldr (\(position, value) -> insertValue (f position) value) IntMap.empty sortedEntries
in IntMap.elems intMap in IntMap.elems intMap
where where
insertValue key value = insertValue key value =