Tutor profile: Edgar S.

Why change from Python 2.7 to Python 3?

Python 2.7 has reached its end-of-life. Since January 2020, no further improvements are made, even security updates. Python 3 is being actively developed. Python 3 brought new improvements, such as separation between string and bytes datatypes (strings are no longer a sequence of byte characters), several improvements in the standard library, print is now a function, support for asynchronous programming with asyncio module including new keywords (async) among others.

What are the basic units of modularity in the Java language?

In a standard Java application, the language provides modularity at the class level, package level or JAR level.

What means to say that an algorithm is $$O(n^2)$$ in terms of time complexity?

The big $$O$$ notation is used to describe the behaviour of the limit of a function. When applied to computer science, it describes how the time the algorithm takes to compute will change when the amount of data changes. In the example $$O(n^2)$$, if $$n$$ represents the size or number of elements processed by the algorithm, the time the algorithm needs to run will grow in a quadratic proportion. In other example, if the algorithm would be $$O(n)$$, the time would increase in a linear fashion, meaning the increment in time for each extra item would always be the same amount.