[배열] 같은 숫자는 싫어 (JAVA)

https://school.programmers.co.kr/learn/courses/30/lessons/12906?language=java 

프로그래머스

풀이1

import java.io.IOException;
import java.util.ArrayList;

class Solution {
    public int[] solution(int []arr) throws IOException {
        int[] answer = {};
        ArrayList<Integer> arrlist = new ArrayList<Integer>();
        int backup = -1;
        for(int i = 0 ; i < arr.length; i++){
            if(backup != arr[i]){
                arrlist.add(arr[i]);
                backup = arr[i];
            }
        }
        answer = new int[arrlist.size()];
        for(int i = 0 ; i < arrlist.size(); i++){
            answer[i] = arrlist.get(i);
        }
        return answer;
    }
}