import java.util.ArrayList;
import java.util.List;


public class Solution {
    public int[] solution(int []arr) {
     List<Integer> checkList = new ArrayList<>();

        for (int i = 0; i < arr.length; i++) {
            int checkListIdx = checkList.size() - 1;

            if (checkListIdx >= 0) {
                int beforeValue = checkList.get(checkListIdx);
                int currentValue = arr[i];

                if (beforeValue == currentValue) continue;
            }

            checkList.add(arr[i]);
        }

        int size = checkList.size();
        int[] answer = new int[size];
        for (int i = 0; i < size; i++) {
            answer[i] = checkList.get(i);
        }

        return answer;
    }
}