103 lines
2.6 KiB
Agda
103 lines
2.6 KiB
Agda
module Day13
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import Prelude
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import Node
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import Aoc
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import Parser
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Point : U
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Point = Int × Int
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instance Add Point where
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(a,b) + (c,d) = (a + c, b + d)
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instance Sub Point where
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(a,b) - (c,d) = (a - c, b - d)
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instance Ord Point where
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(a,b) < (c,d) = a < c || a == c && b < d
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instance Eq Point where
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(a,b) == (c,d) = a == c && b == d
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token : String → Parser Unit
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token str = string str >> ws
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data Machine : U where
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MkMachine : Point → Point → Point → Machine
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-- need Either parser..
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parseButton : Parser Point
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parseButton = do
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token "Button"
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any
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token ":"
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token "X+"
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x <- number
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token ","
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token "Y+"
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y <- number
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match '\n'
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pure (x,y)
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parsePrize : Parser Point
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parsePrize = do
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token "Prize:"
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token "X="
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x <- number
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token ","
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token "Y="
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y <- number
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match '\n'
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pure (x,y)
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pMachine : Parser Machine
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pMachine = MkMachine <$> parseButton <*> parseButton <*> parsePrize <* many (match '\n')
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-- TODO should be a proper primitive, so we can have literals (also need Double)
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ptype BigInt
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pfunc itobi : Int → BigInt := `(x) => BigInt(x)`
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pfunc addbi : BigInt → BigInt → BigInt := `(a,b) => a + b`
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pfunc subbi : BigInt → BigInt → BigInt := `(a,b) => a - b`
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pfunc mulbi : BigInt → BigInt → BigInt := `(a,b) => a * b`
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pfunc divbi : BigInt → BigInt → BigInt := `(a,b) => a / b`
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instance Mul BigInt where a * b = mulbi a b
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instance Div BigInt where a / b = divbi a b
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instance Add BigInt where a + b = addbi a b
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instance Sub BigInt where a - b = subbi a b
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instance Cast Int BigInt where cast x = itobi x
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instance Eq BigInt where a == b = jsEq a b
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instance Show BigInt where show = jsShow
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instance Ord BigInt where a < b = jsLT a b
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calcCost : BigInt → Machine → Maybe BigInt
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calcCost extra (MkMachine (ax, ay) (bx, by) (px, py)) =
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let px = itobi px + extra
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py = itobi py + extra
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b = (px * itobi ay - py * itobi ax) / (itobi ay * itobi bx - itobi by * itobi ax)
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a = (px - itobi bx * b) / itobi ax
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in if a * itobi ax + b * itobi bx == px && a * itobi ay + b * itobi by == py
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then Just (a * itobi 3 + b) else Nothing
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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 (Right (machines,_)) = some pMachine $ unpack text | _ => putStrLn "Parse Error"
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let extra = itobi 0
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let p1 = foldl _+_ (itobi 0) $ mapMaybe (calcCost extra) machines
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putStrLn $ "part1 " ++ show p1
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let extra = itobi 10000000 * itobi 1000000
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let p2 = foldl _+_ (itobi 0) $ mapMaybe (calcCost extra) machines
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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/day13/eg.txt"
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run "aoc2024/day13/input.txt"
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