From 8e9b1f0fa131a3c29dc0d69ae5e9a4cc1d61614f Mon Sep 17 00:00:00 2001
From: kr0st <kr0st@bioreactor.me>
Date: Tue, 2 Dec 2025 00:20:34 +0100
Subject: [PATCH] Accepted solution for problem 9 - palindrome number.

---
 9-palindrome-number.cpp | 26 ++++++++++++++++++++++++++
 main.cpp                |  4 ++++
 2 files changed, 30 insertions(+)
 create mode 100644 9-palindrome-number.cpp

diff --git a/9-palindrome-number.cpp b/9-palindrome-number.cpp
new file mode 100644
index 0000000..efac94f
--- /dev/null
+++ b/9-palindrome-number.cpp
@@ -0,0 +1,26 @@
+#include<iostream>
+
+class PalindromeNumberSolution {
+
+private:
+    void palindromer(unsigned long x, unsigned long *p, unsigned long d, unsigned long *max_d) {
+        if (x == 0) return;
+        if (d > *max_d) *max_d = d;
+        palindromer(x / 10, p, d * 10, max_d);
+        *p += x % 10 * (*max_d / d);
+        return;
+    }
+public:
+    bool isPalindrome(int x) {
+        if (x < 0) return false;
+        if (x < 10) return true;
+
+        auto absX = (unsigned long)x;
+        std::cout << "absX = " << absX << std::endl;
+        unsigned long palindrome = 0;
+        unsigned long max_d = 0;
+        palindromer(absX, &palindrome, 1, &max_d);
+        //std::cout << "reverse(absX) = " << palindrome << std::endl;
+        return absX == palindrome;
+    }
+};
diff --git a/main.cpp b/main.cpp
index 69204b0..8e8d855 100644
--- a/main.cpp
+++ b/main.cpp
@@ -2,6 +2,7 @@
 
 #include "1-two-sum.cpp"
 #include "2-add-two-numbers.cpp"
+#include "9-palindrome-number.cpp"
 
 int main() {
     TwoSumSolution twoSumSolution;
@@ -52,5 +53,8 @@ int main() {
     }
     std::cout << std::endl;
 
+    PalindromeNumberSolution p;
+    std::cout << "Is 1 palindrome? " << p.isPalindrome(1) << std::endl;
+
     return 0;
 }