I tried to resolve this question https://leetcode.com/problems/unique-email-addresses/
The solution uses the index() method.
But it will raise ValueError when the substring is not found and will cause program interruption.
So I think the find() method may be better since it returns -1 on failure.
But I am not sure if the find() method has a better time complexity than the index() method.
Is there a way to find the time complexity of them?