(1) I have a linked list where each node contains a digit.

For example, 1->2->4->6->8.

Here, 1 is the head and 8 is the tail. This represents the number 12,468.

I want to add 1 to this number.

Then, the linked list should become 1->2->4->6->9.

Implement this.

What is the time complexity?

(2) Explain abstract classes and interfaces.

What are their differences?

Give me an example.

(3) Bill has fifty billion dollars. You have one dollar.

Your money doubles each year (e.g., 1 -> 2 -> 4 -> 8 -> ...).

How many years will it take for your money to exceed Bill's?

Give me an answer without a calculator.

I think they are just typical questions.