[알고리즘문제풀기] 등차수열의 특정한 항만 더하기

문제

내가 작성한 정답

class Solution {
    public int solution(int a, int d, boolean[] included) {
        int answer = 0;
        for(int i=0; i<included.length; i++){
            answer += included[i]?a+d*i:0;
        }
        return answer;
    }
}

// stream
import java.util.stream.IntStream;

class Solution {
    public int solution(int a, int d, boolean[] included) {
        return IntStream.range(0,included.length)
                .filter(i->included[i])
                .map(i->a+i*d)
                .sum();
    }
}