Thread: Count Triplets Hackerrank

Hi,
this is my first post and I'm doing an exercise on HackerRank called "Count Triplets".
This is the text:

You are given an array and you need to find number of triplets of indices (i, j, k) such that the elements at those indices are in geometric progression for a given common ratio r and i < j < k.

and this is my code:

public class Solution {
 
    // Complete the countTriplets function below.
    static long countTriplets(List<Long> arr, long r) {
 
        // Long[] a = arr.toArray();
        int counter = 0;
 
        for (int i = 0; i < arr.size() - 2; i++) {
            for (int j = i + 1; j < arr.size() - 1; j++) {
                if (arr.get(j) - arr.get(i) == r) {
                    for (int k = j + 1; k < arr.size(); k++) {
                        if (arr.get(k) - arr.get(j) == r) {
                            System.out.println("(" + arr.get(i) + "," + arr.get(j) + "," + arr.get(k) + ")");
                            counter++;
                            break;
                        }
 
                    }
                }
            }
        }
        return counter;
    }

When I compile this solution , the method returns 0 for each test cases.
I don't understand where the error is.
Thanks for help.