From ea4dfa2548c5aefe45e4f0ce0b7c7fc2e35fb745 Mon Sep 17 00:00:00 2001
From: Nat Lasseter <user@4574.co.uk>
Date: Fri, 6 Dec 2024 10:50:02 +0000
Subject: [Day 05] Part 2: Oh yeah this is simple was overthinking it
---
day05/day05.hs | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
(limited to 'day05')
diff --git a/day05/day05.hs b/day05/day05.hs
index 9118cd2..5c589e7 100644
--- a/day05/day05.hs
+++ b/day05/day05.hs
@@ -23,6 +23,12 @@ valid :: [Rule] -> Update -> Bool
valid rules update =
all (abides update) $ filter (relevant update) rules
+apply :: [Rule] -> Int -> Int -> Ordering
+apply rules a b
+ | [a,b] `elem` rules = LT
+ | [b,a] `elem` rules = GT
+ | otherwise = EQ
+
part11 :: Int -> [Rule] -> [Update] -> Int
part11 acc _ [] = acc
part11 acc rules (h:t)
@@ -33,6 +39,20 @@ part1 :: [Rule] -> [Update] -> Int
part1 rules updates =
part11 0 rules updates
+part21 :: Int -> [Rule] -> [Update] -> Int
+part21 acc _ [] = acc
+part21 acc rules (h:t)
+ | valid rules h = part21 acc rules t
+ | otherwise =
+ let rrules = filter (relevant h) rules
+ sfun = apply rrules
+ inc = middle $ sortBy (sfun) h in
+ part21 (acc + inc) rules t
+
+part2 :: [Rule] -> [Update] -> Int
+part2 rules updates =
+ part21 0 rules updates
+
main = do
file <- readFile "day05.input"
let lns = lines file
@@ -40,4 +60,4 @@ main = do
rules = map (map (read::String->Int)) $ map (splitOn "|") rulesin
updates = map (map (read::String -> Int)) $ map (splitOn ",") updatesin
putStrLn ("Part 1: " ++ (show $ part1 rules updates))
- --putStrLn ("Part 2: " ++ (show $ part2 fst sec))
+ putStrLn ("Part 2: " ++ (show $ part2 rules updates))
--
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