Update number-of-common-factors.cpp

Author: kamyu104

C++/number-of-common-factors.cpp

@@ -1,4 +1,4 @@
-// Time:  O(sqrt(log(min(a, b))))
+// Time:  O(log(min(a, b)) + sqrt(gcd))
 // Space: O(1)
 
 // math