Added palindrome number checker in math folder

Author: Ashutosh-kumar-06

math/palindrome_number.cpp

@@ -0,0 +1,110 @@
+/**
+ * @file
+ * @brief Implementation to check whether a number is a palindrome.
+ *
+ * @details
+ * A palindrome number is a number that remains the same when its digits are
+ * reversed.
+ *
+ * ### Algorithm
+ * - Take the input number `n`.
+ * - Reverse its digits.
+ * - Compare the reversed number with the original.
+ * - If both are equal, then the number is a palindrome.
+ *
+ * @example
+ * Input: 121
+ * Output: Palindrome
+ *
+ * Input: 123
+ * Output: Not Palindrome
+ *
+ * \note This implementation uses integer arithmetic and does not convert to
+ * string.
+ *
+ * @author [Ashutosh kumar](https://github.com/Ashutosh-kumar-06)
+ */
+
+#include <cassert>   /// for assert
+#include <iostream>  /// for IO operations
+
+/**
+ * @namespace math
+ * @brief Mathematical algorithms
+ */
+namespace math {
+/**
+ * @brief Function to check whether a number is a palindrome.
+ * @param n input number
+ * @returns 1 if the number is palindrome, otherwise 0
+ */
+int isPalindrome_number(int n) {
+    if (n < 0) {  // negative numbers are not palindromes
+        return 0;
+    }
+
+    int original = n;
+    int reversed = 0;
+
+    while (n > 0) {
+        int digit = n % 10;
+        reversed = reversed * 10 + digit;
+        n /= 10;
+    }
+
+    return (original == reversed) ? 1 : 0;
+}
+}  // namespace math
+
+/**
+ * @brief Self-test implementations
+ * @returns void
+ */
+static void test() {
+    std::cout << "Test Case 1... ";
+    assert(math::isPalindrome_number(121) == 1);
+    std::cout << "Passed!\n";
+
+    std::cout << "Test Case 2... ";
+    assert(math::isPalindrome_number(123) == 0);
+    std::cout << "Passed!\n";
+
+    std::cout << "Test Case 3... ";
+    assert(math::isPalindrome_number(0) == 1);
+    std::cout << "Passed!\n";
+
+    std::cout << "Test Case 4... ";
+    assert(math::isPalindrome_number(1221) == 1);
+    std::cout << "Passed!\n";
+
+    std::cout << "\nAll test cases have successfully passed!\n";
+}
+
+/**
+ * @brief Optional user input testing
+ * @returns void
+ */
+void user_input_test() {
+    int n = 0;
+    std::cout << "Enter a number: ";
+    std::cin >> n;
+
+    if (math::isPalindrome_number(n)) {
+        std::cout << n << " is a palindrome number.\n";
+    } else {
+        std::cout << n << " is not a palindrome number.\n";
+    }
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on successful execution
+ */
+int main() {
+    test();  // run self-tests
+
+    // Uncomment to test manually
+    // user_input_test();
+
+    return 0;
+}