From 2edcfc5429c2a000b6efe39a14efca83edb6666e Mon Sep 17 00:00:00 2001
From: lourenzo <81989+lourenzo@users.noreply.github.com>
Date: Mon, 13 Jul 2026 03:36:15 +0000
Subject: [PATCH] Optimize Palindromic Number Check by replacing String
 conversions with mathematical reverse

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
---
 src/Problem004PalindromicNumber.java | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/Problem004PalindromicNumber.java b/src/Problem004PalindromicNumber.java
index 94489ef..58172ae 100644
--- a/src/Problem004PalindromicNumber.java
+++ b/src/Problem004PalindromicNumber.java
@@ -5,8 +5,15 @@ void main() {
     .mapToObj(x -> iterate(999, y -> y > 900, y -> y - 1)
       .map(y -> x * y)
       .distinct()
-      .filter((int number) -> String.valueOf(number)
-        .equals(new StringBuilder(String.valueOf(number)).reverse().toString()))
+      .filter((int number) -> {
+        int original = number;
+        int reversed = 0;
+        while (number > 0) {
+          reversed = reversed * 10 + number % 10;
+          number /= 10;
+        }
+        return original == reversed;
+      })
       .boxed())
     .flatMap(stream -> stream)
     .max(Integer::compareTo);