2

1 files changed, 12 insertions, 0 deletions

diff --git a/2024/2.hs b/2024/2.hs
new file mode 100644
index 0000000..e29acec
--- /dev/null
+++ b/2024/2.hs
@@ -0,0 +1,12 @@
+import Data.List (inits, tails)
+
+main :: IO ()
+main = do
+  input <- map (map (read @Int) . words) . lines <$> getContents
+  let safePair a b = 1 <= b - a && b - a <= 3
+  let safeRep l = all (uncurry safePair) (zip l (tail l)) ||
+                    all (uncurry (flip safePair)) (zip l (tail l))
+  print $ sum [fromEnum (safeRep l) | l <- input]
+  let dampened l = zipWith (++) (inits l) (tail (tails l))
+  let safeRep' l = any safeRep (dampened l)
+  print $ sum [fromEnum (safeRep' l) | l <- input]