프로그래머스 - 삼총사

class Solution {
    public int solution(int[] number) {
        int answer = 0;
        int len = number.length;
        for(int i=0; i<len-2; i++){
            for(int j=i+1; j<len-1; j++){
                for(int k=j+1; k<len; k++){
                    if(number[i] + number[j] + number[k] == 0){
                        answer++;
                    }
                }
            }
        }

        return answer;
    }
}