From f604270ea9cd76381bf514b80d0aba33cadc9ec1 Mon Sep 17 00:00:00 2001
From: Sloane Perrault <sloane.perrault@gmail.com>
Date: Wed, 21 Sep 2022 09:19:52 -0400
Subject: [PATCH] fix: remove out-of-bound/Maybe from day 2 part 2

---
 2020/02/README.md |  4 ++++
 2020/02/part2.hs  | 15 +++------------
 2 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/2020/02/README.md b/2020/02/README.md
index 0746f57..f2539c0 100644
--- a/2020/02/README.md
+++ b/2020/02/README.md
@@ -3,3 +3,7 @@
 ## Part 1
 
 Spent some time reading up on how to define a custom instance of `Read`. Pretty simple otherwise. Surprised `countElem` isn't in Prelude.
+
+## Part 2
+
+Off-by-one errors were called out in the puzzle but I still made them. ~Solution can be simplified if I don't need to check for out-of-bounds issues.~ I did this.
diff --git a/2020/02/part2.hs b/2020/02/part2.hs
index 7ffbfc9..f19bdaf 100755
--- a/2020/02/part2.hs
+++ b/2020/02/part2.hs
@@ -25,21 +25,12 @@ solve = show . length . filter (isValidPasswordEntry . readPasswordEntry) . line
 readPasswordEntry :: String -> PasswordEntry
 readPasswordEntry = read
 
-(!!?) :: [a] -> Int -> Maybe a
-[] !!? _ = Nothing
-(x:xs) !!? 0 = Just x
-(_:xs) !!? idx = xs !!? (idx - 1)
-
-maybeToBool (Just a) = a
-maybeToBool Nothing = False
-
 xor :: Bool -> Bool -> Bool
 xor l r = l /= r
 
 isValidPasswordEntry (PasswordEntry pos1 pos2 char pass) =
-    (maybeToBool $ fmap (==char) char1) `xor`
-    (maybeToBool $ fmap (==char) char2)
+    (charAtPos1 == char) `xor` (charAtPos2 == char)
   where
-    char1 = pass !!? (pos1 - 1)
-    char2 = pass !!? (pos2 - 1)
+    charAtPos1 = pass !! (pos1 - 1)
+    charAtPos2 = pass !! (pos2 - 1)