day 1

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

day01.hs

@@ -0,0 +1,40 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+import Data.Char (digitToInt, isDigit)
+import Data.Text qualified as T
+import Lib (readFile')
+
+first :: T.Text -> Int
+first s = f * 10 + l
+  where
+    values = T.filter isDigit s
+    f = (digitToInt . T.head) values
+    l = (digitToInt . T.last) values
+
+second' :: T.Text -> [Int]
+second' s
+  | T.null s = []
+  | T.isPrefixOf "one" s = 1 : second' (T.tail s)
+  | T.isPrefixOf "two" s = 2 : second' (T.tail s)
+  | T.isPrefixOf "three" s = 3 : second' (T.tail s)
+  | T.isPrefixOf "four" s = 4 : second' (T.tail s)
+  | T.isPrefixOf "five" s = 5 : second' (T.tail s)
+  | T.isPrefixOf "six" s = 6 : second' (T.tail s)
+  | T.isPrefixOf "seven" s = 7 : second' (T.tail s)
+  | T.isPrefixOf "eight" s = 8 : second' (T.tail s)
+  | T.isPrefixOf "nine" s = 9 : second' (T.tail s)
+  | isDigit (T.head s) = digitToInt (T.head s) : second' (T.tail s)
+  | otherwise = second' (T.tail s)
+
+second :: T.Text -> Int
+second s = head values * 10 + last values
+  where
+    values = second' s
+
+main :: IO ()
+main = do
+  input <- T.lines <$> readFile' "day01.in"
+  putStr "Q1: "
+  print . sum . map first $ input
+  putStr "Q2: "
+  print . sum . map second $ input