1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
module Day22B where
import System.Environment (getArgs)
import Text.Printf
import Data.List.Split (splitOn)
-- Types
data Player = P1 | P2;
-- Top = First
type Deck = [Int];
-- (P1, P2)
type State = (Deck, Deck);
-- Parsing
parseDeck :: String -> Deck
parseDeck = map read . tail . lines
-- Parse the input
parseInput :: String -> State
parseInput xs = (p1, p2)
where [p1, p2] = map parseDeck $ splitOn "\n\n" xs
-- Parse a file given the path
-- Returns list of instructions
parseFromFile :: String -> IO State
parseFromFile s = do
contents <- readFile s;
return $ parseInput contents;
takeTurn :: State -> [State] -> (State, [State])
takeTurn s@(c1:p1, c2:p2) h | s `elem` h = ((p1 ++ p2 ++ [c1, c2], []), h)
| length p1 >= c1
&& length p2 >= c2 = case getPlayerWinner ((take c1 p1, take c2 p2), []) of
P1 -> p1Win
P2 -> p2Win
| c1 > c2 = p1Win
| otherwise = p2Win
where p1Win = ((p1 ++ [c1, c2], p2), h')
p2Win = ((p1, p2 ++ [c2, c1]), h')
h' = s : h
takeTurn ([], _) _ = error "game is over!"
takeTurn (_, []) _ = error "game is over!"
getPlayerWinner :: (State, [State]) -> Player
getPlayerWinner ((_, []), _) = P1
getPlayerWinner (([], _), _) = P2
getPlayerWinner (s, h) = getPlayerWinner $ takeTurn s h
getWinner :: (State, [State]) -> Deck
getWinner ((p1, []), _) = p1
getWinner (([], p2), _) = p2
getWinner (s, h) = getWinner $ takeTurn s h
getScore :: Deck -> Int
getScore d = sum $ zipWith (*) (reverse [1..length d]) d
-- runghc --ghc-arg='-package split' 22a.hs inputs/day22
main :: IO ()
main = do
args <- getArgs;
s <- parseFromFile (head args);
let winnerScore = getScore $ getWinner (s, []);
printf "Answer = %d\n" winnerScore :: IO ();
return ();
|
