82 lines
2.4 KiB
Haskell
Executable File
82 lines
2.4 KiB
Haskell
Executable File
#! /usr/bin/env -S"ANSWER=42" nix-shell
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#! nix-shell -p ghcid
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#! nix-shell -p "haskellPackages.ghcWithPackages (p: with p; [])"
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#! nix-shell -i "ghcid -c 'ghci -Wall' -T main"
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{-# LANGUAGE OverloadedStrings #-}
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import Data.List (intersperse)
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testData :: [String]
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testData = [ "..##......."
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, "#...#...#.."
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, ".#....#..#."
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, "..#.#...#.#"
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, ".#...##..#."
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, "..#.##....."
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, ".#.#.#....#"
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, ".#........#"
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, "#.##...#..."
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, "#...##....#"
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, ".#..#...#.#"
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]
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data Position = Position { x_::Int, y_::Int }
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instance Show (Position)
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where
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show p = "("<>show (x_ p)<>","<>show (y_ p)<>")"
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-- Returns a half-line starting on (0,0) and following the (x*a,x*b) eq:
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line :: Int -> Int -> [Position]
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line a b = Position 0 0 : [ Position (x*a) (x*b) | x <- [1..] ]
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-- Starting at the top-left corner of your map and following a slope of right 3
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-- and down 1, how many trees would you encounter?
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-- Requirements for this first task:
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-- - datastructure supporting random-access (or similar) interface (lists would work)
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-- - function generating a list of (x,y) coordinate to check
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-- - must have 2D datastructure, since it's infinite on 1D (x axis)
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-- - in this version at least, there's no need to modify the datastructure, so
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-- it can be read-only, or even just a function taking a position and returning
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-- SquareSortEmpty or SquareSortTree
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data SquareSort = SquareSortTree | SquareSortEmpty
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instance Show SquareSort
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where
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show SquareSortTree = "#"
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show SquareSortEmpty = "."
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char2ss :: Char -> Maybe SquareSort
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char2ss '#' = Just SquareSortTree
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char2ss '.' = Just SquareSortEmpty
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char2ss _ = Nothing
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str2sss :: String -> Maybe [SquareSort]
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str2sss = sequence . (map char2ss)
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newtype Grid = Grid [[SquareSort]]
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instance Show (Grid)
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where
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show (Grid x) = intersperse '\n' $ map show x
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parseInput :: [String] -> Maybe Grid
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parseInput x = Grid <$> sequence ( (map str2sss) x )
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getSquareSortAtPosition :: Grid -> Position -> SquareSort
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getSquareSortAtPosition (Grid grid) (Position x y) =
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grid !! y !! (x `mod` n)
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where
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n = length (grid !! 0)
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main :: IO ()
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main = do
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putStrLn "Day 3 - Part 1"
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print $ take 5 $ line 3 1
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let (Just parsedTestData) = parseInput testData
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print parsedTestData
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print $ getSquareSortAtPosition parsedTestData (Position 3 0)
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