[프로그래머스] 시저 암호

class Solution {
    public String solution(String s, int n) {
        StringBuilder sb = new StringBuilder();
        char[] arr = s.toCharArray();
        
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] >= 'A' && arr[i] <= 'Z') sb.append((char)((arr[i] - 'A' + n) % 26 + 'A'));
            else if (arr[i] >= 'a' && arr[i] <= 'z') sb.append((char)((arr[i] - 'a' + n) % 26 + 'a'));
            else sb.append(arr[i]);
        }
        return sb.toString();
    }
}