[프로그래머스/Java] 시저 암호

-Code

class Solution {
    public String solution(String s, int n) {
        StringBuilder answer = new StringBuilder();
        String lower = "abcdefghijklmnopqrstuvwxyz";
        String upper = lower.toUpperCase();
        for (char c : s.toCharArray()) {
            char w = c;
            if (Character.isLowerCase(w)) {
                w = lower.charAt((w + n - 'a') % 26);
            } else if (Character.isUpperCase(w)) {
                w = upper.charAt((w + n - 'A') % 26);
            }
            answer.append(w);
        }
        return answer.toString();
    }
}