Day 1

inputs/day1-example.input

@@ -0,0 +1,6 @@
+3   4
+4   3
+2   5
+1   3
+3   9
+3   3

inputs/day1-example.solution

@@ -0,0 +1 @@
+11

package.yaml

@@ -12,6 +12,8 @@ dependencies:
   - matrix
   - vector
   - containers
+  - text
+  - scientific
 
 executables:
   aoc24:

src/Day1.hs

@@ -2,7 +2,51 @@
 
 module Day1 where
 
+-- import Debug.Trace
+
+import qualified Data.Attoparsec.Text as P
+import qualified Data.Text.IO as T
+import Data.Scientific (coefficient)
+import Data.List (sort)
+import Data.Bifunctor (bimap)
+import Data.Either (fromRight)
+
+parseInput :: P.Parser [(Integer,Integer)]
+parseInput = parseLine `P.sepBy` P.endOfLine
+
+parseLine :: P.Parser (Integer,Integer)
+parseLine = do
+  num1 <- coefficient <$> P.scientific
+  _ <- P.many1 P.space
+  num2 <- coefficient <$> P.scientific
+  pure (num1,num2)
+
+-- calculating distance
+solveA :: [(Integer,Integer)] -> Integer
+solveA = sum
+       . fmap (\(x,y) -> abs (y-x))
+       . uncurry zip
+       . bimap sort sort
+       . unzip
+
+-- calculating similarity score
+solveB :: [(Integer,Integer)] -> Integer
+solveB xs = sum ys
+  where
+    ys = uncurry similarity $ unzip xs
+    similarity as bs = map go as
+      where
+        -- Find how many occurences n of a in bs
+        -- Return a*n
+        go :: Integer -> Integer
+        go a = a * toInteger (length (filter (== a) bs))
+
 main :: IO ()
 main = do
+  _input <- T.readFile "inputs/day1-example.input"
+  input <- T.readFile "inputs/day1.input"
   putStrLn "Part 1"
+  let xs = fromRight [] $ P.parseOnly parseInput input
+  print $ solveA xs
   putStrLn "Part 2"
+  print $ solveB xs