55 lines
1.5 KiB
Agda
55 lines
1.5 KiB
Agda
module Day11b
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import Prelude
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import Node
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import Aoc
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import SortedMap
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-- Alternate version that doesn't use string
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infixl 7 _%_
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pfunc _%_ : Int → Int → Int := `(x,y) => x % y`
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-- 32 bit ints are too small
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pfunc div53 : Int → Int → Int := `(x,y) => Math.floor(x / y)`
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stone : Int → Either Int (Int × Int)
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stone num = if num == 0 then Left 1 else go num num 1
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where
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go : Int → Int → Int → Either Int (Int × Int)
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go a b mod =
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if b == 0 then Right (a, num % mod)
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else if b < 10 then Left (2024 * num)
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else go (div53 a 10) (div53 b 100) (mod * 10)
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step : List (Int × Int) → List (Int × Int)
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step xs = go Nil xs
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where
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go : List (Int × Int) → List (Int × Int) → List (Int × Int)
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go acc Nil = acc
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go acc ((x,c) :: xs) = case stone x of
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Left a => go ((a,c) :: acc) xs
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Right (a,b) => go ((a,c) :: (b,c) :: acc) xs
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iter : Int → SortedMap Int Int → Int
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iter count parts = let x = go count parts in foldl _+_ 0 $ map snd $ toList x
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where
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go : Int → SortedMap Int Int → SortedMap Int Int
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go 0 stuff = stuff
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go x stuff = go (x - 1) $ foldMap _+_ EmptyMap $ step $ toList stuff
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run : String -> IO Unit
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run fn = do
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putStrLn fn
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text <- readFile fn
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let stuff = foldMap _+_ EmptyMap $ map (\ x => (stringToInt x, 1)) $ split (trim text) " "
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let p1 = iter 25 stuff
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putStrLn $ "part1 " ++ show p1
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let p2 = iter 75 stuff
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putStrLn $ "part2 " ++ show p2
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main : IO Unit
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main = do
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run "aoc2024/day11/eg.txt"
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run "aoc2024/day11/input.txt"
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