feat: part 2-2

advent-of-code-2024.ipkg

@@ -15,4 +15,4 @@ main = Main
 modules = Main, Utils, AllDays,
           Data.Problem,
           Day1.Part1, Day1.Part2,
-          Day2.Part1
+          Day2.Part1, Day2.Part2

src/AllDays.idr

@@ -3,3 +3,4 @@ module AllDays
 import public Day1.Part1
 import public Day1.Part2
 import public Day2.Part1
+import public Day2.Part2

src/Day2/Part2.idr

@@ -0,0 +1,27 @@
+module Day2.Part2
+
+import Data.List
+import Data.List1
+import Data.String
+import Utils
+
+import Day2.Part1
+
+%default total
+
+--- DATA
+
+reductions : Report -> List Report
+reductions (x ::: []) = []
+reductions (x ::: [y]) = [y ::: [], x ::: []]
+reductions (x ::: (y :: xs)) =
+  (y ::: xs) :: map (x `cons`) (assert_total $ reductions (y ::: xs))
+
+isSafe' : Report -> Bool
+isSafe' rep = isSafe rep || any isSafe (reductions rep)
+
+--- SOLUTION
+
+export
+solution : String -> Maybe Nat
+solution inp = count isSafe' <$> parseInput inp

src/Main.idr

@@ -18,7 +18,7 @@ import AllDays
 ||| The latest problem that has been solved.
 -- NOTE: UPDATE AFTER EACH SOLUTION
 latest : Problem
-latest = Pr 2 Part1
+latest = Pr 2 Part2
 
 
 solMap : SortedMap Problem (String -> String)