From cb0d65fa6f7a250713467b9e2369d2ce85aaef25 Mon Sep 17 00:00:00 2001
From: Matt Russell <MattRussellUK@gmail.com>
Date: Tue, 3 Dec 2024 13:49:09 +0000
Subject: [PATCH] wip

---
 Aoc2024/Day03/Solve.lean | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/Aoc2024/Day03/Solve.lean b/Aoc2024/Day03/Solve.lean
index be29cfa..0eaad99 100644
--- a/Aoc2024/Day03/Solve.lean
+++ b/Aoc2024/Day03/Solve.lean
@@ -5,23 +5,24 @@ import Aoc2024.Day03.Types
 
 def Instruction.value : Instruction -> Int
   | Instruction.mul n m => n * m
-  | Instruction.do => 1
-  | Instruction.dont => 1
+  | _ => 1
 
 def solvePart1 (s : String) : Int := findInstructions s |>.sumBy (·.value)
 
 #guard solvePart1 exampleInputPart1 == 161
 
-private def filterInstructions (enabled : Bool) : List Instruction -> List Instruction
+private def findEnabledMulInstructions (enabled : Bool) : List Instruction -> List Instruction
   | [] => []
-  | List.cons instruction rest =>
+  | instruction :: rest =>
     match instruction with
       | Instruction.mul m n =>
-        if enabled then List.cons (Instruction.mul m n) (filterInstructions enabled rest)
-        else filterInstructions enabled rest
-      | Instruction.do => filterInstructions true rest
-      | Instruction.dont => filterInstructions false rest
+        if enabled then
+          Instruction.mul m n ::findEnabledMulInstructions enabled rest
+        else
+          findEnabledMulInstructions enabled rest
+      | Instruction.do => findEnabledMulInstructions true rest
+      | Instruction.dont => findEnabledMulInstructions false rest
 
-def solvePart2 (s : String) : Int := findInstructions s |> filterInstructions true |> List.sumBy (·.value)
+def solvePart2 (s : String) : Int := findInstructions s |> findEnabledMulInstructions true |>.sumBy (·.value)
 
 #guard solvePart2 exampleInputPart2 == 48