From 95f13675ddb056dcea2268684c937b0d53f8fa9a Mon Sep 17 00:00:00 2001
From: Jens Kadenbach <jens.kadenbach@smartsteuer.de>
Date: Tue, 6 Dec 2022 11:01:54 +0100
Subject: [PATCH] Cleanup Day 6 - still bad naive algorithm

---
 src/Day6.hs      | 33 +++++++++++++++++----------------
 test/Day6Spec.hs | 21 +++++++++------------
 2 files changed, 26 insertions(+), 28 deletions(-)

diff --git a/src/Day6.hs b/src/Day6.hs
index 532a93b..e3da6bc 100644
--- a/src/Day6.hs
+++ b/src/Day6.hs
@@ -1,27 +1,28 @@
 module Day6 (
-  findMarker,
-  findMarker',
+  findEnd,
   findStart,
   isUnique,
   day6
 ) where
 
-findMarker :: String -> Maybe Int
-findMarker = findMarker' 4 0 ""
+findMarker :: Int -> String -> Maybe Int
+findMarker windowSize = findMarker' 0 ""
+  where
+  findMarker' :: Int -> String -> String -> Maybe Int
+  findMarker' offset window  []
+    | isUnique window && length window == windowSize = Just offset
+    | otherwise = Nothing
+  findMarker' offset window (c:cs)
+    | length window < windowSize = findMarker' (offset + 1) (c:window) cs
+    | not (isUnique window) = findMarker' (offset + 1) (c:init window) cs
+    | isUnique window = Just offset
+    | otherwise = Nothing
 
 findStart :: String -> Maybe Int
-findStart = findMarker' 14 0 ""
-
-findMarker' :: Int -> Int -> String -> String -> Maybe Int
-findMarker' windowSize offset window  []
-  | isUnique window && length window == windowSize = Just offset
-  | otherwise = Nothing
-findMarker' windowSize offset window (c:cs)
-  | length window < windowSize = findMarker' windowSize (offset + 1) (c:window) cs
-  | not (isUnique window) = findMarker' windowSize (offset + 1) (c:init window) cs
-  | isUnique window = Just offset
-  | otherwise = Nothing
+findStart = findMarker 14 
 
+findEnd :: String -> Maybe Int
+findEnd = findMarker 4
 
 isUnique :: (Eq a) => [a] -> Bool
 isUnique [] = True
@@ -31,7 +32,7 @@ day6 :: IO ()
 day6 = do
    input <- readFile "ressources/day06-input"
    putStrLn "Day6"
-   let offset = findMarker input
+   let offset = findEnd input
    putStrLn ("Found end marker at " ++ show offset)
    let startOffset = findStart input
    putStrLn ("Found start marker at " ++ show startOffset)
diff --git a/test/Day6Spec.hs b/test/Day6Spec.hs
index cfcda00..7d4660c 100644
--- a/test/Day6Spec.hs
+++ b/test/Day6Spec.hs
@@ -11,21 +11,18 @@ spec =
         isUnique "abc" `shouldBe` True
         isUnique "abca" `shouldBe` False
         isUnique "cabc" `shouldBe` False
-      it "finds the marker in the next iteration" $ do
-        findMarker' 4 3 "abc" "d" `shouldBe` Just 4
-        findMarker' 4 4 "bcd" "e" `shouldBe` Just 5
       it "finds nothing if nothing is there" $ do
-        findMarker "abcb" `shouldBe` Nothing
-        findMarker "abcabcb" `shouldBe` Nothing
+        findEnd "abcb" `shouldBe` Nothing
+        findEnd "abcabcb" `shouldBe` Nothing
       it "finds the marker in the beginning" $ do
-        findMarker "abcd" `shouldBe` Just 4
-        findMarker "aabcd" `shouldBe` Just 5
+        findEnd "abcd" `shouldBe` Just 4
+        findEnd "aabcd" `shouldBe` Just 5
       it "finds a marker" $ do
-        findMarker "mjqjpqmgbljsphdztnvjfqwrcgsmlb"`shouldBe` Just 7
-        findMarker "bvwbjplbgvbhsrlpgdmjqwftvncz" `shouldBe` Just 5
-        findMarker "nppdvjthqldpwncqszvftbrmjlhg" `shouldBe` Just 6
-        findMarker "nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg" `shouldBe` Just 10
-        findMarker "zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw" `shouldBe` Just 11
+        findEnd "mjqjpqmgbljsphdztnvjfqwrcgsmlb"`shouldBe` Just 7
+        findEnd "bvwbjplbgvbhsrlpgdmjqwftvncz" `shouldBe` Just 5
+        findEnd "nppdvjthqldpwncqszvftbrmjlhg" `shouldBe` Just 6
+        findEnd "nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg" `shouldBe` Just 10
+        findEnd "zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw" `shouldBe` Just 11
     describe "Part 2" $ do
       it "finds start of message marker" $ do
         findStart "mjqjpqmgbljsphdztnvjfqwrcgsmlb"`shouldBe` Just 19