Fixes - in gcd_fixed.py, comments about mistakes - in gcd.py

gcd.py

@@ -1,17 +1,18 @@
 # Wrong gcd find 5 mistakes
 
-def gcd(a, b):
-    assert a <= 0 and b >= 0
+def gcd(a, b): # mistake 1 - we do not specify explicitly that the type must be int
+    assert a <= 0 and b >= 0  # mistake 2 - a will be asserted to be *less* than 0 in this case;
+    # mistake 3 - there is no error message in case assertion fails - it is optional, but still better to have it
     while a and b:
         if a > b:
-            a = a / b
+            a = a / b  # mistake 4 - we have to use modulo in order to know both the remainder and to escape the loop once the remainder would be 0
         else:
-            b = b / a
-    return min(a, b)
+            b = b / a  # same mistake 4
+    return min(a, b)  # mistake 5 - should be max, as we are looking for the *greatest* divisor
 
 # Examples
 
 # gcd(10, 0) => 10
 # gcd(123, 3) => 3
 # gcd(1000000, 64) => 64
-# gcd(0, 0) => 0
+# gcd(0, 0) => 0

gcd_fixed.py

@@ -0,0 +1,14 @@
+def gcd(a:int, b:int):
+    assert a >= 0 and b >= 0, "Please do not use negative integers"
+    while a and b:
+        if a > b:
+            a = a % b
+        else:
+            b = b % a
+    return max(a, b)
+
+print(gcd(10, 0))
+print(gcd(123, 3))
+print(gcd(1000000, 64))
+print(gcd(0, 0))
+print(gcd(32, 64))