[Programmers] 세로 읽기

https://school.programmers.co.kr/learn/courses/30/lessons/181904

프로그래머스

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Python

def solution(s, m, c):
    return s[c-1::m]

Java

class Solution {
    public String solution(String my_string, int m, int c) {
        StringBuilder sb = new StringBuilder();

        int startIdx = c - 1;

        while(startIdx < my_string.length()){
            sb.append(my_string.charAt(startIdx));
            startIdx += m;
        }
        return sb.toString();
    }
}