private static int solve(String s) {
        if (s == null || s.length() == 0)
            return 0;
        int count = 0;
        for (int i = 0; i < 128; i++) {
            String row = s + "-" + i;
            String hash = KnotHash_10.calculateKnotHash(row);
            for (int j = 0; j < hash.length(); j++) {
                count += hexBitCount(String.valueOf(hash.charAt(j)));
            }
        }

        return count;
    }
Why Did you create this class? what does it do?
src/adventofcode/DiskDefragmentation_14.java