adding happy number problem

labs/11_hash_tables/happy_number.cpp

@@ -0,0 +1,23 @@
+#include <iostream>
+
+bool isHappy(int n) {
+}
+
+int main() {
+	// Test cases
+	// 2, 4, 5, 6, 17, 18, 20 are not happy numbers.
+	// 1, 7, 10, 13, 19, 23, 28, 68 are not happy numbers.
+
+    int testCases[] = {2,4,5,6,17,18,20,1,7,10,13,19,23,28,68};
+
+    for (int n : testCases) {
+        if (isHappy(n)) {
+            std::cout << n << " is a happy number." << std::endl;
+        } else {
+            std::cout << n << " is not a happy number." << std::endl;
+        }
+    }
+
+    return 0;
+}
+