int arr[] = new int[] { 0, 1, 1, 2, 3, 5, 8, 13, 21 };
 int n = 6;
 n = arr[arr[n] / 2];
 System.out.println(n);

What will be the output?

The answer for this is harder for a beginner than it might look at first, as I did not know that I have to do some math in order to tell the result of this question.

It took me a bit to understand what arr[arr[n] / 2] is and how it works, but a good advice I read on my journey to learn how to code helped me here: Write each and every step down on a sheet of paper with a pencil.

By doing so, I found out arr[arr[n] / 2] is a nested value and from math I knew to solve brackets first. Which made me conclude, I will have to work my way from the inside out to solve it.

The first thing to do was to put in a value for the placeholder n, which obviously is 6, as the second line of the code says exactly this: int n = 6.

It now was a little clearer to me, because that the value reads arr[arr[6] / 2], and I could go on by defining the arr in the next bracket, because it looked like something that must be divided by 2.

Having in mind the basics of an array, I could identify arr[6] as the 6th index position of the array, which is the number 8.

I filled this into the brackets, it reads arr[8 / 2] and could do some basic math on it. So 8 / 2 = 4, and there was another value to put in arr[arr[4]].

At this point it was super clear to me that it now reads “index of arr is the value on index position 4 of the array”, which is the number 3. So the output will be 3.

I hope this might help some of you to understand how to read and solve such a value, and to understand what the code is doing.

Cheers