class Solution {
    public String solution(String cipher, int code) {
        String answer = "";
        return answer;
    }
}

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해결법

방법 1

class Solution {
    public String solution(String cipher, int code) {
        String answer = "";
        
        for (int i = code-1; i < cipher.length(); i+=code) {
            answer += cipher.charAt(i);
        }
        
        return answer;
    }
}

• charAt()

방법 2

class Solution {
    public String solution(String cipher, int code) {
        String answer = "";

        for (int i = code; i <= cipher.length(); i+=code) {
            answer += cipher.substring(i - 1, i);
        }

        return answer;
    }
}

• substring()

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암호 해독 Lv. 0