Fixed Issues

calculator.py

@@ -1,55 +1,40 @@
 def add(a, b):
     # ISSUE 1: This function incorrectly handles negative numbers
-    if a < 0 or b < 0:
-        return abs(a) + abs(b)  # BUG: Should preserve negatives
     return a + b
 
 def subtract(a, b):
     return a - b  # This one is correct
 
 def multiply(a, b):
     # ISSUE 2: This function has performance issues with large numbers
-    result = 0
-    if b > 0:
-        for i in range(b):
-            result += a
-    elif b < 0:
-        for i in range(abs(b)):
-            result -= a
-    return result
+    return a * b
 
 def divide(a, b):
     # ISSUE 3: This function doesn't handle division by zero properly
     if b == 0:
-        return float('inf')  # BUG: Should raise an exception instead
+        raise ZeroDivisionError("Cannot divide by zero")  # BUG: Should raise an exception instead
     return a / b
 
 def power(base, exponent):
     # ISSUE 4: This function has multiple bugs
-    if exponent == 0:
-        return 1
-    elif exponent < 0:
-        # BUG: Doesn't handle negative exponents correctly
-        return 1 / power(base, exponent)
-
-    result = 1
-    for i in range(exponent):
-        result *= base
-    return result
+    return base ** exponent
 
 def factorial(n):
     # ISSUE 5: This function has recursion issues
-    if n < 0:
-        return -1  # BUG: Should raise ValueError for negative inputs
+    if not isinstance(n, int) or n < 0:
+        raise ValueError("Factorial is only defined for non-negative integers")
     if n == 0:
-        return 1
-    return n * factorial(n - 1)
+        return 1  # Base case to stop recursion
+    else:
+        return n * factorial(n - 1)
 
+import math
 def is_prime(n):
     # ISSUE 6: This function has logic errors
     if n < 2:
         return False
-    for i in range(2, n):
+    # Check for divisors from 2 up to the square root of n
+    for i in range(2, int(math.sqrt(n)) + 1):
         if n % i == 0:
-            return False
-    return True
+            return False  # Found a divisor, so it's not prime
+    return True # No divisors were found, so it is prime