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bfs: use a Set for visited nodes

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hi 2025-08-12 13:28:23 +00:00
parent 7f0afa76a6
commit 56a8dd2b30
2 changed files with 6 additions and 4 deletions
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8
Logic/Graph.hs
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@ -1,7 +1,9 @@
module Logic.Graph where
bfs :: Eq a => a -> a -> (a -> [(edge, a)]) -> Maybe [edge]
bfs goal start getEdges = reverse <$> aux [([], start)] []
import Data.Set (Set, insert)
bfs :: (Eq a, Ord a) => a -> a -> (a -> [(edge, a)]) -> Maybe [edge]
bfs goal start getEdges = reverse <$> aux [([], start)] mempty
where
aux [] _ = Nothing
aux ((path, vertex):queue) visited
@ -12,7 +14,7 @@ bfs goal start getEdges = reverse <$> aux [([], start)] []
case filter (\(_, v) -> v == goal) new of
[] ->
let queue' = queue ++ map (\(edge, next) -> (edge:path, next)) new
in aux queue' (vertex:visited)
in aux queue' $ insert vertex visited
((edge, _):_) -> Just (edge:path)
getUnvisitedAdjacent vertex visited =