From 3933ed1e609d1ed0ca93d784c7e43a50c5d88551 Mon Sep 17 00:00:00 2001
From: germax26 <maximburykin1@gmail.com>
Date: Mon, 2 Dec 2024 18:55:47 +1100
Subject: [PATCH] Add 2024 Days 01/02 in Haskell

---
 2024/day01/day01.hs | 18 ++++++++++++++++++
 2024/day02/day02.hs | 23 +++++++++++++++++++++++
 aoc.hs              | 12 ++++++++++++
 3 files changed, 53 insertions(+)
 create mode 100644 2024/day01/day01.hs
 create mode 100644 2024/day02/day02.hs
 create mode 100644 aoc.hs

diff --git a/2024/day01/day01.hs b/2024/day01/day01.hs
new file mode 100644
index 0000000..74a112c
--- /dev/null
+++ b/2024/day01/day01.hs
@@ -0,0 +1,18 @@
+import Data.List ( sort, group )
+import Data.Maybe ( fromMaybe )
+import Aoc ( aocMain )
+
+parseFile :: [String] -> ([Int], [Int])
+parseFile lines = unzip [(a, b) | line <- lines, let [a, b] = map read $ words line]
+
+part1 :: ([Int], [Int]) -> Int
+part1 (list1, list2) = sum $ zipWith (curry (abs . uncurry (-))) (sort list1) (sort list2)
+
+part2 :: ([Int], [Int]) -> Int
+part2 (list1, list2) = sum $ map score list1
+    where
+        score n = n * fromMaybe 0 (lookup n count)
+        count = map (\xs -> (head xs, length xs)) $ group $ sort list2
+
+main :: IO ()
+main = aocMain parseFile part1 part2
diff --git a/2024/day02/day02.hs b/2024/day02/day02.hs
new file mode 100644
index 0000000..ac0cf0d
--- /dev/null
+++ b/2024/day02/day02.hs
@@ -0,0 +1,23 @@
+import Aoc ( aocMain )
+
+parseFile :: [String] -> [[Int]]
+parseFile = map (map read . words)
+
+part1 :: [[Int]] -> Int
+part1 reports =
+    length $ filter isSafe $ map differences reports
+    where
+        differences xs = zipWith (-) xs (tail xs)
+        isGradual dx = 1 <= abs dx && abs dx <= 3
+        isSafe dxs = all isGradual dxs && (all (<0) dxs || all (>0) dxs)
+
+part2 :: [[Int]] -> Int
+part2 reports = 
+    length $ filter isSafe $ map remove1 reports
+    where
+        remove n xs = let (front, back) = splitAt n xs in front ++ tail back
+        remove1 report = map (`remove` report) [0..length report-1]
+        isSafe = (>0) . part1
+
+main :: IO ()
+main = aocMain parseFile part1 part2
\ No newline at end of file
diff --git a/aoc.hs b/aoc.hs
new file mode 100644
index 0000000..da16c4a
--- /dev/null
+++ b/aoc.hs
@@ -0,0 +1,12 @@
+module Aoc where
+
+aocMain :: Show p => ([String] -> p) -> (p -> Int) -> (p -> Int) -> IO ()
+aocMain parseFile part1 part2 = do
+    contents <- readFile "input.txt"
+    let input = parseFile $ lines contents
+    -- print $ "Input: " ++ show input
+    print $ "Part 1: " ++ show (part1 input)
+    print $ "Part 2: " ++ show (part2 input)
+
+enumerate :: [a] -> [(Int, a)]
+enumerate xs = zip [0..length xs] xs
\ No newline at end of file