jasterv/aoc2024-haskell
1
0
Fork 0
mirror of https://codeberg.org/JasterV/aoc2024-haskell.git synced 2026-04-26 18:10:05 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

make sure that Matrix.groupWith sorts the values before grouping

Browse source
This commit is contained in:
JasterV 2025-03-26 00:26:48 +01:00
parent ed7e95b59d
commit fda3ec56bc
1 changed files with 5 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
src/Day4/Matrix.hs
View file

@ -14,8 +14,8 @@ where
import Data.HashMap.Lazy (HashMap)
import qualified Data.HashMap.Lazy as HashMap
import Data.IntMap.Lazy (IntMap)
import qualified Data.IntMap.Lazy as IntMap
import Data.List (sortOn)
import Data.Maybe
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,
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 f (Matrix hmap) =
let intMap :: IntMap [v]
intMap = HashMap.foldrWithKey (insertValue . f) IntMap.empty hmap
let sortedEntries = sortOn fst $ HashMap.toList hmap
intMap = foldr (\(position, value) -> insertValue (f position) value) IntMap.empty sortedEntries
in IntMap.elems intMap
where
insertValue key value =