first commit

day1.hs

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+module Main where
+
+main :: IO ()
+main = do
+  raw <- readFile "day1.txt"
+  let ls = map read $ lines raw :: [Integer]
+   in do
+     case (solveA ls) of
+       Nothing -> error "no answer"
+       (Just x) -> putStrLn $ "day1a: " ++ (show x)
+     case (solveB ls) of
+       Nothing -> error "no answer"
+       (Just x) -> putStrLn $ "day1b: " ++ (show x)
+
+solveA :: [Integer] -> Maybe Integer
+solveA [] = Nothing
+solveA xs = Just $ (\(x,y) -> x * y) lsa
+  where
+    lsa = head [ (x,y) | x <- xs, y <- xs, x + y == 2020 ]
+
+solveB :: [Integer] -> Maybe Integer
+solveB [] = Nothing
+solveB xs = Just $ (\(x,y,z) -> x * y * z) lsb
+  where
+    lsb = head [ (x,y,z) | x <- xs, y <- xs, z <- xs, x + y + z == 2020 ]

day1.txt

@@ -0,0 +1,200 @@
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+1621
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