What I learned today is about Agorithm and complexity. For those who graduated from Computer science know well about this subject, but for me and my friend quite difficult to understand because our background education was not in Computer science. We had discussed two topics today. First topic is about Copy List and second topics is about Concat . I know algorithm is very important to computer programming. But as I said my background education was Electrical engineering not Computer science, that's why i don't know how to learn this difficult thing. Like or dislike i have no choice, need to study hard and hoping that i can pass this difficult situation.