+-- Using the idea of canonical representation of buildings from
+-- https://andars.github.io/aoc_day11.html by Andrew Foote,
+-- plus my extension of represening the pairs as an integer.
+
+-- This version is A* search, using a priority queue for the agenda.
+
import Data.List (subsequences, (\\), sort, sortOn, nub, findIndices)
import Data.Ord (comparing)
import Data.Char (isDigit)
data Item = Generator String | Microchip String deriving (Show, Eq)
type Floor = [Item]
data Building = Building Int [Floor] deriving (Show, Eq)
--- data CBuilding = CBuilding Int [(Int, Int)] deriving (Show, Eq)
data CBuilding = CBuilding Int Integer deriving (Show, Eq)
data Agendum = Agendum {current :: Building, trail :: [CBuilding], cost :: Int}
type Agenda = P.MinPQueue Int Agendum
candidate = current agendum
previous = trail agendum
succs = legalSuccessors $ successors candidate
- -- nonloops = (succs \\ previous) \\ closed
- excludable = previous ++ closed
- nonloops = filter (\s -> not $ (canonical s) `elem` excludable) succs
+ nonloops = filter (\s -> not $ (canonical s) `elem` closed) succs
newCandidates = map (\a -> (cost a, a)) $ map (\n -> makeAgendum n) nonloops
makeAgendum new = Agendum {current = new,
trail = (canonical candidate):previous,