public static ArrayList<Integer> duplicates(int arr[], int n) {

// code here

// create Set, add unique elements

// if element not in Set, add to dups

ArrayList<Integer> dups = new ArrayList<>();

Arrays.sort(arr);

Set<Integer> uniques = new HashSet<>();

for (int num : arr) {

System.out.println("13Uniques: " + uniques);

if (!uniques.contains(num)) {

uniques.add(num);

System.out.println("Uniques: " + uniques);

}

else if (!dups.contains(num)) {

dups.add(num);

System.out.println("Dups: " + dups);

}

}

if (dups.size() == 0) {

dups.add(-1);

}

return dups;

// create frequency HashMap

//

// ArrayList<Integer> dupes = new ArrayList<>();

// ArrayList<Integer> uniques = new ArrayList<>();

// for (int element : arr) {

// if (!uniques.contains(element)) {

// uniques.add(element);

// } else {

// dupes.add(element);

// }

// }

// if (dupes.size() == 0) {

// dupes.add(-1);

// }

// Collections.sort(dupes);

// return dupes;

}

public static void main(String[] args) {

// int arr[] = {0, 3, 1, 2};

// int n = 4;

// int arr[] = {2,3,1,2,3};

// int n = 5;

int arr[] = {13, 9, 25, 1, 1, 0, 22, 13, 22, 20, 3, 8, 11, 25, 10, 3, 15, 11, 19, 20, 2, 4, 25, 14, 23, 14};

int n = 26;

ArrayList<Integer> output = duplicates(arr, n);

System.out.println("Output: " + output); // Output:

}