[문제링크 - 프로그래머스 - 암호 해독] https://school.programmers.co.kr/learn/courses/30/lessons/120892
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;
}
}