[Programmers] 같은 숫자는 싫어 (Java)

https://programmers.co.kr/learn/courses/30/lessons/12906

Solution

import java.util.*;

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

        for (int i = 0; i < arr.length - 1; i++) {
            if (arr[i] == arr[i + 1]) {
                if (i == arr.length - 2) { // last
                    answer.add(arr[i + 1]);
                }
                continue; // key point
            } else {
                answer.add(arr[i]);
                if (i == arr.length - 2) { // last
                    answer.add(arr[i + 1]);
                }
            }

        }

        return answer;
    }

    public static void main(String[] args) {
        System.out.println(solution(new int[]{1, 1, 3, 3, 0, 1, 1}));
        System.out.println(solution(new int[]{4, 4, 4, 3, 3}));
        System.out.println(solution(new int[]{4, 4, 4, 3, 2, 1}));

    }
}

Another Solution

import java.util.*;

public class Solution {
    public static int[] solution(int[] arr) {
        ArrayList<Integer> tempList = new ArrayList<Integer>();
        int preNum = 10; // arr[i] -> 1 ~ 9
        for (int num : arr) { // arr -> num
            if (preNum != num) {
                tempList.add(num);
            }
            preNum = num; // num -> preNum
        }

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

        return answer;
    }

    public static void main(String[] args) {
        System.out.println(Arrays.toString(solution(new int[]{1, 1, 3, 3, 0, 1, 1})));
        System.out.println(Arrays.toString(solution(new int[]{4, 4, 4, 3, 3})));
        System.out.println(Arrays.toString(solution(new int[]{4, 4, 4, 3, 2, 1})));

    }
}