Day nine

day-09-haskell/src/Common.hs

@@ -0,0 +1,31 @@
+module Common where
+
+data BlockType = Empty | Allocated Int
+
+instance Show BlockType where
+  show Empty = "(empty)"
+  show (Allocated blockId) = show blockId
+instance Eq BlockType where
+  (==) Empty Empty = True
+  (==) (Allocated a) (Allocated b) = True
+  (==) _ _ = False
+
+type Block = (BlockType, Int)
+length :: Block -> Int
+length (_, l) = l
+
+parseBlocks :: String -> [Block]
+parseBlocks = startWithBlock 0
+  where
+    startWithBlock :: Int -> String -> [Block]
+    startWithBlock _ [] = []
+    startWithBlock blockId (size:rest)
+      | size >= '0' && size <= '9' = (Allocated blockId, read [size]) : startWithEmpty (blockId + 1) rest
+      | otherwise = startWithBlock blockId rest
+
+    startWithEmpty :: Int -> String -> [Block]
+    startWithEmpty _ [] = []
+    startWithEmpty blockId (size:rest)
+      | size >= '0' && size <= '9' = (Empty, read [size]) : startWithBlock blockId rest
+      | otherwise = startWithEmpty blockId rest
+