private static int solve2(String s) {
        if (s == null || s.length() == 0)
            return 0;
        if (s.length() == 1)
            return Integer.parseInt(s);
        int sum = 0;
        int n = s.length();
        for (int i = 0; i < s.length(); i++) {
            char current = s.charAt(i);
            char next = s.charAt((i + n / 2) % n);
            if (next == current)
                sum += (current - '0');
        }
        return sum;
    }
Why Did you create this class? what does it do?
src/adventofcode/Captcha_1.java