Implemented GCD function

students_submissions/gcd_dg232.py

@@ -0,0 +1,37 @@
+def gcd(a: int, b: int) -> int:
+    """
+    Calculate the greatest common divisor (GCD) of two integers a and b
+    using the Euclidean algorithm recursively.
+
+    Returns:
+        int: The GCD of a and b, or None if input is invalid.
+    """
+    # Check for invalid input
+    if not isinstance(a, int) or not isinstance(b, int):
+        print("This is error, both inputs must be integers.")
+        return None
+
+    # Handle edge cases
+    if a == 0 and b == 0:
+        print("this is error, GCD is undefined for a = 0 and b = 0.")
+        return None
+
+    # Make numbers positive (GCD is always non-negative)
+    a, b = abs(a), abs(b)
+
+    # Base case
+    if b == 0:
+        return a
+
+    # Recursive case
+    return gcd(b, a % b)
+
+
+if __name__ == "__main__":
+    print(gcd(54, 24))    
+    print(gcd(48, 18))    
+    print(gcd(101, 10))   
+    print(gcd(-36, 60))  
+    print(gcd(0, 5))      
+    print(gcd(0, 0))      
+    print(gcd(13, 17))