Update greatest-common-divisor-of-strings.py

Author: kamyu104

Python/greatest-common-divisor-of-strings.py

@@ -16,7 +16,7 @@ def check(s, common):
                 i = (i+1)%len(common)
             return True
 
-        def gcd(a, b):  # Time: O((logn)^2)
+        def gcd(a, b):  # Time: O(log(min(a, b)))
             while b:
                 a, b = b, a % b
             return a