37 lines
1.4 KiB
Haskell
37 lines
1.4 KiB
Haskell
import Data.List.Split
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import Data.List
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import qualified Data.Set as Set
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import Data.Maybe
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main = do
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content <- readFile "input"
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let input = map (splitOn ",") (lines content)
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let parsedinput = map (map parseone) input
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let trace1 = tracewire (head parsedinput) (0,0) [(0,0)]
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let trace2 = tracewire (last parsedinput) (0,0) [(0,0)]
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print (day3a trace1 trace2)
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print (day3b trace1 trace2)
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parseone :: String -> (Char, Int)
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parseone xs = (head xs, read $ tail xs)
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tracewire :: [(Char,Int)] -> (Int,Int) -> [(Int,Int)] -> [(Int,Int)]
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tracewire [] _ x = x
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tracewire ((x,n):xs) (accx,accy) trc
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| x=='U'=tracewire xs (accx,accy+n) (trc++[(accx,accy+i) | i<-[1..n]])
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| x=='R'=tracewire xs (accx+n,accy) (trc++[(accx+i,accy) | i<-[1..n]])
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| x=='D'=tracewire xs (accx,accy-n) (trc++[(accx,accy-i) | i<-[1..n]])
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| x=='L'=tracewire xs (accx-n,accy) (trc++[(accx-i,accy) | i<-[1..n]])
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day3a :: [(Int,Int)] -> [(Int,Int)] -> Int
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day3a xs ys = Set.findMin $ Set.map manhattan (intersections xs ys)
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where manhattan (x,y) = abs x + abs y
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intersections :: [(Int,Int)] -> [(Int,Int)] -> Set.Set (Int, Int)
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intersections xs ys = Set.delete (0,0) crossset
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where crossset = (Set.fromList xs) `Set.intersection` (Set.fromList ys)
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day3b xs ys = minimum [let f = fromJust . findIndex (==x) in f xs + f ys
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| x<-Set.toList $ intersections xs ys]
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