Day 1

Day1/puzzle1.hs

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+import Data.List (transpose, sort)
+import System.IO
+
+listDistance :: [Int] -> [Int] -> Int
+listDistance xs ys = sum $ map abs $ zipWith (-) (sort xs) (sort ys)
+
+main = do
+    contents <- lines <$> readFile "day1.txt"
+    let [x, y] = transpose $ map read . words <$> contents
+        distance = listDistance x y
+    print distance

Day1/puzzle2.hs

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+import Data.List (transpose, sort, group)
+import System.IO
+
+similarityScore :: [Int] -> [Int] -> Int
+similarityScore xs ys = let elemsY = [ (head y, length y) | y <- (group . sort) ys ]
+                            xy = [ (x, snd y) | x <- xs, y <- elemsY, x == fst y ]
+                        in sum [ uncurry (*) x | x <- xy ]
+
+main = do
+    contents <- lines <$> readFile "day1.txt"
+    let [x, y] = transpose $ map read . words <$> contents
+        score = similarityScore x y
+    print score