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100 doors: Difference between revisions
Added Idris Solution
(Added Idris Solution) |
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Line 3,728:
every write("Door ",i := 1 to 100," is ",dMap[i])
end</lang>
=={{header|Idris}}==
<lang idris>import Data.Vect
-- Creates list from 0 to n (not including n)
upTo : (m : Nat) -> Vect m (Fin m)
upTo Z = []
upTo (S n) = 0 :: (map FS (upTo n))
data DoorState = DoorOpen | DoorClosed
toggleDoor : DoorState -> DoorState
toggleDoor DoorOpen = DoorClosed
toggleDoor DoorClosed = DoorOpen
isOpen : DoorState -> Bool
isOpen DoorOpen = True
isOpen DoorClosed = False
initialDoors : Vect 100 DoorState
initialDoors = fromList $ map (\_ => DoorClosed) [1..100]
iterate : (n : Fin m) -> Vect m DoorState -> Vect m DoorState
iterate n doors {m} =
map (\(idx, doorState) =>
if ((S (finToNat idx)) `mod` (S (finToNat n))) == Z
then toggleDoor doorState
else doorState)
(zip (upTo m) doors)
-- Returns all doors left open at the end
solveDoors : List (Fin 100)
solveDoors =
findIndices isOpen $ foldl (\doors,val => iterate val doors) initialDoors (upTo 100)
main : IO ()
main = print $ map (\n => S (finToNat n)) solveDoors</lang>
=={{header|Inform 7}}==
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