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