From d8dc1a750a5678fa4445b1e927e8a8051c1d07e1 Mon Sep 17 00:00:00 2001
From: Klotz <julius.klotz01@sap.com>
Date: Wed, 3 Dec 2025 13:19:29 +0100
Subject: [PATCH] improved code quality day2

---
 bin/main.ml |  1 +
 lib/day2.ml | 25 +++++++++++++------------
 lib/dune    |  3 ++-
 3 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/bin/main.ml b/bin/main.ml
index 3ee6bed..74c46a0 100644
--- a/bin/main.ml
+++ b/bin/main.ml
@@ -1,3 +1,4 @@
 let () = Printf.printf "Solution Day 1 part 1: %i\n" Aoc25.Day1.day1_part1
 let () = Printf.printf "Solution Day 1 part 2: %i\n" Aoc25.Day1.day1_part2
 let () = Printf.printf "Solution Day 2 part 1: %i\n" Aoc25.Day2.day2_part1
+let () = Printf.printf "Solution Day 2 part 2: %i\n" Aoc25.Day2.day2_part2
diff --git a/lib/day2.ml b/lib/day2.ml
index f357b0e..10ba501 100644
--- a/lib/day2.ml
+++ b/lib/day2.ml
@@ -5,6 +5,8 @@ let is_valid ((start, ending): string * string) : bool =
   let end_length = String.length ending in
   let filtered_out =   start_length mod 2 != 0 && end_length mod 2 != 0 && start_length == end_length in
   not filtered_out
+  
+
 
 let generate_tuple (value : string) : (string * string) =
   let split = String.split_on_char '-' value in
@@ -25,34 +27,33 @@ let is_invalid (number: int) : bool =
   let invalid = is_even && first_part = last_part in
   invalid
 
+  let is_invalid_2 (number: int) : bool =
+    let number_string = string_of_int number in
+    let pattern = Str.regexp "\\(.+\\)\\1+$" in
+    Str.string_match pattern number_string 0
   
-let calculate_for_line ((start, ending) : (string * string)) : int =
+let calculate_for_line ((start, ending) : (string * string)) (inv: int -> bool) : int =
   let start_number = int_of_string start in
   let end_number = int_of_string ending in
   let rec loop i acc = 
     if i > end_number then acc
-    else loop (i + 1) (acc + if is_invalid i then i else 0)
+    else loop (i + 1) (acc + if inv i then i else 0)
   in
   loop start_number 0
-
   
-let rec calculate_invalidities (entries: (string * string) list) (result : int): int = 
-  match entries with 
-  | x :: xs -> calculate_invalidities xs (result + calculate_for_line x)
-  | _ -> result
-
-
+let calculate_invalidities entries inv =
+  List.fold_left (fun acc entry -> acc + calculate_for_line entry inv) 0 entries
 
 let solve_part1 (inputs: string list) : int = 
   let inputs = generate_pairs inputs in 
   let filtered = List.filter is_valid inputs in
-  let result = 0 in
-  calculate_invalidities filtered result
+  calculate_invalidities filtered is_invalid
 
   
 
 let solve_part2 (inputs: string list) : int = 
-  List.length inputs
+  let inputs = generate_pairs inputs in
+  calculate_invalidities inputs is_invalid_2
   
 let day2_part1 : int = 
   solve_part1 input
diff --git a/lib/dune b/lib/dune
index 85360cf..70714db 100644
--- a/lib/dune
+++ b/lib/dune
@@ -1,2 +1,3 @@
 (library
- (name aoc25))
+ (name aoc25)
+ (libraries str))