feat(math): add palindrome number checker using standard headers

Author: siddharthhkk

math/palindrome_number.cpp

@@ -1,11 +1,26 @@
+/**
+ * @file
+ * @brief Check if a given number is a palindrome
+ * @details
+ * This program defines a function `is_palindrome_number()` which checks whether
+ * a number reads the same backward as forward.
+ * Negative numbers are treated as non-palindromic.
+ *
+ * @see https://en.wikipedia.org/wiki/Palindrome
+ */
+
 #include <iostream>
 #include <string>
 #include <vector>
 
-// Function to check if a number is a palindrome
+/**
+ * @brief Checks if an integer is a palindrome number.
+ * @param n The number to check.
+ * @return `true` if `n` is a palindrome, otherwise `false`.
+ */
 bool is_palindrome_number(long long n) {
     if (n < 0)
-        return false;  // Negative numbers are not palindromes
+        return false;
     std::string s = std::to_string(n);
     int i = 0, j = static_cast<int>(s.size()) - 1;
     while (i < j) {
@@ -18,6 +33,9 @@ bool is_palindrome_number(long long n) {
 }
 
 #ifdef RUN_LOCAL
+/**
+ * @brief Example test cases for the palindrome number checker.
+ */
 int main() {
     std::vector<long long> tests = {121, -121, 10, 12321, 0};
     for (auto t : tests) {