Add Day 5, Puzzle 2 solution

README.md

@@ -6,5 +6,5 @@
 |02 |★ ★  |08 |     |
 |03 |★ ★  |09 |     |
 |04 |★ ★  |10 |     |
-|05 |★    |11 |     |
+|05 |★ ★  |11 |     |
 |06 |     |12 |     |

src/Day05.hs

@@ -2,9 +2,11 @@
 
 module Day05
   ( day05_1,
+    day05_2,
   )
 where
 
+import Data.List (sortOn)
 import Data.List.Split (splitOn)
 
 getRange :: String -> (Int, Int)
@@ -20,6 +22,14 @@ isFresh ingredient (r : rs)
   | ingredient >= fst r && ingredient <= snd r = True
   | otherwise = isFresh ingredient rs
 
+countIngredients :: [(Int, Int)] -> Int -> Int
+countIngredients [] tot = tot
+countIngredients [r] tot = snd r - fst r + 1 + tot
+countIngredients (r : s : rs) tot
+  | snd r >= snd s = countIngredients (r : rs) tot
+  | snd r >= fst s = countIngredients ((fst r, fst s - 1) : s : rs) tot
+  | otherwise = countIngredients (s : rs) (snd r - fst r + 1 + tot)
+
 parseInput :: IO [String]
 parseInput = do
   lines <$> readFile "input/day5.txt"
@@ -32,3 +42,12 @@ day05_1 = do
   putStrLn $
     "Day 5, Puzzle 1 solution: "
       ++ show (length freshIngredients)
+
+day05_2 :: IO ()
+day05_2 = do
+  input <- parseInput
+  let ranges = sortOn fst . sortOn snd . map getRange $ takeWhile (/= "") input
+      result = countIngredients ranges 0
+  putStrLn $
+    "Day 5, Puzzle 2 solution: "
+      ++ show result

src/Main.hs

@@ -4,7 +4,7 @@ import Day01 (day01_1, day01_2)
 import Day02 (day02_1, day02_2)
 import Day03 (day03_1, day03_2)
 import Day04 (day04_1, day04_2)
-import Day05 (day05_1)
+import Day05 (day05_1, day05_2)
 import System.Environment (getArgs)
 
 main :: IO ()
@@ -32,8 +32,10 @@ main = do
       day04_1
       day04_2
     "5" : "1" : _ -> day05_1
+    "5" : "2" : _ -> day05_2
     "5" : _ -> do
       day05_1
+      day05_2
     "all" : _ -> do
       day01_1
       day01_2
@@ -44,4 +46,5 @@ main = do
       day04_1
       day04_2
       day05_1
+      day05_2
     _ -> error "Not implemented"