102 lines
2.6 KiB
Agda
102 lines
2.6 KiB
Agda
module Day2
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import Prelude
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Draw : U
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Draw = Int × Int × Int
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data Game : U where
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MkGame : Int -> List Draw -> Game
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-- Original had class and instance...
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-- Add, Sub, Mul, Neg
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-- NB this is not lazy!
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infixl 5 _&&_
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_&&_ : Bool -> Bool -> Bool
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a && b = case a of
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False => False
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True => b
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max : Int -> Int -> Int
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max x y = case x < y of
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True => y
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False => x
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pfunc repr : {a : U} -> a -> String := `(a,o) => ''+o`
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pfunc jrepr : {a : U} -> a -> String := `(a,o) => JSON.stringify(o, null, ' ')`
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pfunc toInt : String -> Int := `s => Number(s)`
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mapM : {a b c : U} -> (a -> Either b c) -> List a -> Either b (List c)
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mapM f Nil = Right Nil
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mapM f (x :: xs) = case f x of
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Left msg => Left msg
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Right v => case mapM f xs of
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Left msg => Left msg
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Right vs => Right $ v :: vs
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maxd : Draw -> Draw -> Draw
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maxd (a,b,c) (d,e,f) = (max a d, max b e, max c f)
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lte : Draw -> Draw -> Bool
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lte (a,b,c) (d,e,f) = a <= d && b <= e && c <= f
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parseColor : String -> Either String Draw
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parseColor line = case split line " " of
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(n :: "red" :: Nil) => Right (toInt n,0,0)
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(n :: "green" :: Nil) => Right (0,toInt n,0)
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(n :: "blue" :: Nil) => Right (0,0,toInt n)
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x => Left $ "Bad draw" ++ repr x
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parseDraw : String -> Either String Draw
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parseDraw line = case mapM parseColor $ split line ", " of
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Right parts => Right $ foldl maxd (0,0,0) parts
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Left err => Left err
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parseGame : String -> Either String Game
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parseGame line =
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-- Need the Idris | sugar...
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case split line ": " of
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-- this is splitting on the Nil instead of the a
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(a :: b :: Nil) => case split a " " of
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("Game" :: ns :: Nil) =>
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let num = toInt ns in
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case mapM parseDraw $ split b "; " of
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Right parts => Right $ MkGame num parts
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Left err => Left err
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_ => Left "No Game"
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_ => Left $ "No colon in " ++ line
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part1 : List Game -> Int
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part1 Nil = 0
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part1 (MkGame n parts :: rest) =
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let total = foldl maxd (0,0,0) parts in
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case lte total (12,13,14) of
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True => n + part1 rest
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False => part1 rest
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part2 : List Game -> Int
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part2 Nil = 0
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part2 (MkGame n parts :: rest) =
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case foldl maxd (0,0,0) parts of
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(a,b,c) => a * b * c + part2 rest
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-- readFile not in browser / playground
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-- run : String -> IO Unit
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-- run fn = do
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-- text <- readFile fn
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-- case mapM parseGame (split (trim text) "\n") of
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-- Left err => putStrLn $ "fail " ++ err
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-- Right games => do
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-- putStrLn "part1"
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-- printLn (part1 games)
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-- putStrLn "part2"
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-- printLn (part2 games)
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-- main : IO Unit
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-- main = do
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-- run "aoc2023/day2/eg.txt"
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-- run "aoc2023/day2/input.txt"
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