Add day2 and readd day1

.gitignore

@@ -1,7 +1,9 @@
 # Ignore everything without extension
 *
+!*.*
 !*/
 
 *.in
 *.hi
 *.o
+*.prof

Day1/Day1A.hs

@@ -0,0 +1,8 @@
+module Day1A where
+
+read' :: String -> Int
+read' ('+':str) = read str
+read' str = read str
+
+main :: IO ()
+main = interact $ show . sum . map read' . lines

Day1/Day1B.hs

@@ -0,0 +1,14 @@
+module Day1B where
+
+import Day1A (read')
+import qualified Data.IntSet as S
+
+handle :: Int -> S.IntSet -> [Int] -> Int
+handle freq history (nextDelta:xs)
+  | S.member freq history = freq  -- When the frequency is in the history set, return it
+  | otherwise             = handle (freq + nextDelta) (S.insert freq history) xs  -- Recurse otherwise
+handle _ _ _ = error "xs should not be empty :("
+
+main :: IO ()
+main = interact $ show . handle 0 S.empty . deltaFreqs
+  where deltaFreqs = cycle . map read' . lines  -- Convert input to Ints and repeat infinitely

Day2/Day2A.hs

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+module Day2A where
+
+import qualified Data.IntMap as IM
+import Data.Char (ord)
+
+out :: String -> Int -> Int
+out id' n = min (length $ IM.filter (==n) counts) 1
+  where counts = foldr (\c -> IM.insertWith (+) (ord c) 1) IM.empty id'
+
+handleId :: String -> (Int, Int)
+handleId id' = (out id' 2, out id' 3)
+
+add2 :: Num a => (a, a) -> (a, a) -> (a, a)
+add2 (a, b) (x, y) = (a + x, b + y)
+
+main :: IO ()
+main = interact $ show . uncurry (*) . counts . lines
+  where counts = foldr (add2 . handleId) (0, 0)

Day2/Day2B.hs

@@ -0,0 +1,25 @@
+{-# LANGUAGE TupleSections #-}
+module Day2B where
+import Data.List (find)
+import qualified Data.Sequence as S
+import qualified Data.Foldable as F
+
+dist' :: Int -> (S.Seq Char) -> String -> String -> (Int, String)
+dist' n common (a:x) (b:y)
+  | a == b    = dist' n (common S.|> a) x y
+  | otherwise = dist' (n + 1) common x y
+dist' n common _ _ = (n, F.toList common)
+
+dist :: String -> String -> (Int, String)
+dist = dist' 0 S.empty
+
+combinations :: [String] -> [(String, String)]
+combinations (x:y:xs) = (x, y):(combinations (y:xs))
+combinations [] = []
+
+distances :: [(String, String)] -> String
+distances xs = result
+  where Just(_, result) = find (\(x, _) -> x == 1) $ map (uncurry dist) xs
+
+main :: IO ()
+main = interact $ distances . combinations . lines