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Diffstat (limited to '2019')
-rw-r--r--2019/18.hs36
1 files changed, 15 insertions, 21 deletions
diff --git a/2019/18.hs b/2019/18.hs
index c84f710..c758446 100644
--- a/2019/18.hs
+++ b/2019/18.hs
@@ -125,18 +125,18 @@ reachable (Implicit _ graph distarr) keys start = snd (go 0 (SIS.singleton start
then (seen, result')
else foldl (\(sn, rs) c -> go (dist + distarr A.! (at, c)) sn c rs) (seen', result') nextNonpearls
-searchBFS :: SmallIntSet -> Implicit -> (Int, [Int])
-searchBFS allKeys implicit@(Implicit nstart _ distarr) =
+searchBFS :: Implicit -> (Int, [Int])
+searchBFS implicit@(Implicit nstart _ _) =
let startNodes = [52 + i | i <- [0..nstart-1]]
- in go 0 (Set.singleton (heuristic startNodes SIS.empty, 0, startNodes, SIS.empty, [])) Map.empty
+ in go 0 (Set.singleton (0, startNodes, SIS.empty, [])) Map.empty
where
-- pqueue: f-val, distance, nodes, keys, key order
-- visited: nodes, keys => distance
- go :: Int -> Set (Int, Int, [Int], SmallIntSet, [Int]) -> Map ([Int], SmallIntSet) Int -> (Int, [Int])
+ go :: Int -> Set (Int, [Int], SmallIntSet, [Int]) -> Map ([Int], SmallIntSet) Int -> (Int, [Int])
go ctr pqueue visited =
- let ((heurval, dist, curnodes, keys, keyorder), newpqueue) = Set.deleteFindMin pqueue
+ let ((dist, curnodes, keys, keyorder), newpqueue) = Set.deleteFindMin pqueue
reachLists = [reachable implicit keys node | node <- curnodes]
- nextStates = [(dist + stepDist + heuristic stepNodes stepKeys, dist + stepDist, stepNodes, stepKeys, stepC : keyorder)
+ nextStates = [(dist + stepDist, stepNodes, stepKeys, stepC : keyorder)
| (robotIdx, reach) <- zip [0..] reachLists
, (stepC, stepDist) <- IntMap.assocs reach
, let stepKeys = SIS.insert stepC keys
@@ -146,23 +146,18 @@ searchBFS allKeys implicit@(Implicit nstart _ distarr) =
visited' = Map.insert (curnodes, keys) dist visited
pqueue' = newpqueue <> Set.fromList nextStates
result =
- if all IntMap.null reachLists
- then if heurval == dist then (dist, keyorder) else error ("heurval - dist = " ++ show (heurval - dist) ++ " in terminal state!")
- else go (ctr + 1) pqueue' visited'
+ if maybe True (dist <) (Map.lookup (curnodes, keys) visited)
+ then if all IntMap.null reachLists
+ then (dist, keyorder)
+ else go (ctr + 1) pqueue' visited'
+ else go (ctr + 1) newpqueue visited
in -- (if ctr `rem` 20000 == 0 || all IntMap.null reachLists
- -- then trace ("go #pqueue=" ++ show (Set.size pqueue) ++ " #visited=" ++ show (Map.size visited)
- -- ++ " curnodes=" ++ show curnodes ++ " dist=" ++ show dist ++ " heurval=" ++ show heurval ++ " keys=" ++ show keyorder
+ -- then trace ("go ctr=" ++ show ctr ++ " #pqueue=" ++ show (Set.size pqueue) ++ " #visited=" ++ show (Map.size visited)
+ -- ++ " curnodes=" ++ show curnodes ++ " dist=" ++ show dist ++ " keys=" ++ show keyorder
-- {- ++ " next->" ++ show nextStates -})
-- else id)
result
- heuristic :: [Int] -> SmallIntSet -> Int
- heuristic _curnodes keys =
- let remainKeys = allKeys SIS.\\ keys
- allDists = [distarr A.! (x, y) | x:xs <- tails (SIS.toList remainKeys), y <- xs]
- distLowerBound = sum (take (SIS.size remainKeys - 1) (sort (filter (/= -1) allDists)))
- in distLowerBound
-
main :: IO ()
main = do
stringbd <- getInput 18
@@ -170,8 +165,7 @@ main = do
startpos = fromJust (lookup '@' (map (\(x,y) -> (y,x)) (Map.assocs bd)))
let imgraph = implicitGraph bd [startpos]
- allKeys = SIS.fromList [ord c - ord 'a' | c <- Map.elems bd, isLower c]
- print (fst (searchBFS allKeys imgraph))
+ print (fst (searchBFS imgraph))
let (sx, sy) = startpos
bd2 = Map.unionWith (const id) bd
@@ -180,4 +174,4 @@ main = do
,((sx-1,sy+1), '3'), ((sx,sy+1), '#'), ((sx+1,sy+1), '4')])
imgraph2 = implicitGraph bd2 [(sx-1,sy-1), (sx+1,sy-1), (sx-1,sy+1), (sx+1,sy+1)]
- print (fst (searchBFS allKeys imgraph2))
+ print (fst (searchBFS imgraph2))