이진수 더하기

class Solution {
    public String solution(String bin1, String bin2) {
        long newValue = Long.parseLong(bin1, 2) + Long.parseLong(bin2, 2);

        return Long.toBinaryString(newValue);
    }
}

삼총사

class Solution {
    public int solution(int[] number) {
        int answer = 0;

        for (int i = 0; i < number.length; i++) {
            int i1 = number[i];

            for (int j = i + 1; j < number.length; j++) {
                int i2 = number[j];

                for (int k = j + 1; k < number.length; k++) {
                    int i3 = number[k];

                    if (i1 + i2 + i3 == 0) {
                        answer++;
                    }
                }
            }
        }

        return answer;
    }
}