Someone please explain this

Question

https://code.sololearn.com/cuut9j45TF65/?ref=app

Answer 1

This code represents the Fibonacci sequence.
This looks like:
0 1 1 2 3 5 8 13 21...
It begins with 0 and 1, and then the next element is calculated as the sum of the last two numbers:
0 + 1 = 1
1 + 1 = 2
1 + 2 = 3
2 + 3 = 5
And so on.
The code follows the same logic. The "base case" is the first two numbers:
f(0)=0
f(1)=1
Then all the next numbers are calculated recursively from the previous elements:
f(2) = f(0) + f(1) = 0 + 1 = 1
and so on.