day 3

day3/app/Main.hs

@@ -0,0 +1,45 @@
+module Main (main) where
+
+import System.Environment
+import Data.Char (digitToInt)
+
+main :: IO ()
+main = do
+    args <- getArgs
+    input <- readFile $ head args
+    let banks = lines input
+    let values = map (getDigits 12) banks
+    let numberValues = map digitsToNumber values
+    print numberValues
+    print $ sum numberValues
+
+digitsToNumber :: [Int] -> Int
+digitsToNumber [] = 0
+digitsToNumber [x] = x
+digitsToNumber (x:xs) = x * 10 ^ (length xs) + digitsToNumber xs
+-- 
+-- highestDigits :: (Int, Int) -> [Char] -> (Int, Int)
+-- highestDigits (d1, d2) [] = (d1, d2)
+-- highestDigits (d1, d2) [h] = let digit = digitToInt h in (d1, if digit > d2 then digit else d2)
+-- highestDigits (d1, d2) (h:t)
+--     | digitToInt h > d1 = highestDigits (digitToInt h, 0) t
+--     | digitToInt h > d2 = highestDigits (d1, digitToInt h) t
+--     | otherwise = highestDigits (d1, d2) t
+--
+
+getDigits :: Int -> [Char] -> [Int]
+getDigits n str = getDigitsInternal [] n $ map digitToInt str
+
+getDigitsInternal :: [Int] -> Int -> [Int] -> [Int]
+getDigitsInternal acc 0 _ = acc
+getDigitsInternal acc n lst = let nxt = highestDigitBeforeN (0, 0) (1, length lst - n + 1) lst in
+    getDigitsInternal (acc ++ [fst nxt]) (n - 1) (drop (snd nxt) lst)
+    
+
+highestDigitBeforeN :: (Int, Int) -> (Int, Int) -> [Int] -> (Int, Int)
+highestDigitBeforeN acc _ [] = acc
+highestDigitBeforeN (maxDigit, maxPos) (pos, n) (x:xs)
+    | pos <= n = if x > maxDigit
+        then highestDigitBeforeN (x, pos) (pos + 1, n) xs
+        else highestDigitBeforeN (maxDigit, maxPos) (pos + 1, n) xs
+    | otherwise = (maxDigit, maxPos)