From c165c3ab1c58c85f8de4653a91379158ecc91d53 Mon Sep 17 00:00:00 2001
From: Neil Smith <neil.git@njae.me.uk>
Date: Sun, 19 Dec 2021 10:05:49 +0000
Subject: [PATCH] Reordered bits

---
 advent16/Main.hs | 64 +++++++++++++++++++++---------------------------
 1 file changed, 28 insertions(+), 36 deletions(-)

diff --git a/advent16/Main.hs b/advent16/Main.hs
index d9fc4a6..ab14272 100644
--- a/advent16/Main.hs
+++ b/advent16/Main.hs
@@ -1,4 +1,4 @@
--- Writeup at https://work.njae.me.uk/2021/12/16/advent-of-code-2021-day-14/
+-- Writeup at https://work.njae.me.uk/2021/12/18/advent-of-code-2021-day-16/
 
 import Data.Word
 import Data.Bits
@@ -55,23 +55,34 @@ getBool :: ParseTrans Bool
 getBool = 
   do  bs <- get
       let value = head $ BS.unpack $ BS.take 1 bs
-      put (BS.drop 1 bs)
+      put $ BS.drop 1 bs
       return value
 
 getInt :: Int64 -> ParseTrans Integer
 getInt n = 
   do  bs <- get
       let value = BS.toBits $ BS.take n bs
-      put (BS.drop n bs)
+      put $ BS.drop n bs
       return value
 
 getBits :: Int64 -> ParseTrans Transmission
 getBits n = 
   do  bs <- get
       let bits = BS.take n bs
-      put (BS.drop n bs)
+      put $ BS.drop n bs
       return bits
 
+getPacket :: ParseTrans Packet
+getPacket =
+  do version <- getInt 3
+     pType <- getInt 3
+     payload <- if pType == 4
+                then do val <- getLiteral
+                        return $ Literal val
+                else do contents <- getOperatorContents
+                        return $ mkOperator pType contents
+     return $ Packet version payload
+
 getLiteral :: ParseTrans Integer
 getLiteral = getLiteralAcc 0
 
@@ -81,38 +92,8 @@ getLiteralAcc acc =
       nybble <- getInt 4
       let acc' = acc * 16 + nybble
       if continues
-      then (do getLiteralAcc acc')
-      else (return acc')
-
--- getLiteralPacket :: ParseTrans (Integer, Integer, Integer)
--- getLiteralPacket = 
---   do  version <- getInt 3
---       pType <- getInt 3
---       val <- getLiteral
---       return (version, pType, val)
-
-
-getPacket :: ParseTrans Packet
-getPacket =
-  do version <- getInt 3
-     pType <- getInt 3
-     payload <- case pType of 
-        4 -> do val <- getLiteral
-                return $ Literal val
-        _ -> do contents <- getOperatorContents
-                return $ mkOperator pType contents
-     return $ Packet version payload
-
-mkOperator :: Integer -> [Packet] -> PacketContents
-mkOperator pType contents = case pType of
-  0 -> Sum contents
-  1 -> Product contents
-  2 -> Minimum contents
-  3 -> Maximum contents
-  5 -> GreaterThan (contents!!0) (contents!!1)
-  6 -> LessThan (contents!!0) (contents!!1)
-  7 -> EqualTo (contents!!0) (contents!!1)
-
+      then do getLiteralAcc acc'
+      else return acc'
 
 getOperatorContents :: ParseTrans [Packet]
 getOperatorContents =
@@ -137,6 +118,17 @@ getPacketsByCount n =
      ps <- getPacketsByCount (n - 1)
      return (p : ps)
 
+mkOperator :: Integer -> [Packet] -> PacketContents
+mkOperator pType contents = case pType of
+  0 -> Sum contents
+  1 -> Product contents
+  2 -> Minimum contents
+  3 -> Maximum contents
+  5 -> GreaterThan (contents!!0) (contents!!1)
+  6 -> LessThan (contents!!0) (contents!!1)
+  7 -> EqualTo (contents!!0) (contents!!1)
+
+
 packetVersionSum :: Packet -> Integer
 packetVersionSum (Packet version contents) = 
   version + (contentsVersionSum contents)
-- 
2.34.1