private static int solve2(String s) {
        if (s == null || s.length() == 0)
            return 0;
        int count = 0;
        int[][] a = new int[128][128];
        for (int i = 0; i < 128; i++) {
            String row = s + "-" + i;
            String hash = KnotHash_10.calculateKnotHash(row);
            StringBuilder builder = new StringBuilder();
            for (int j = 0; j < hash.length(); j++) {
                String bin = hexToBin(String.valueOf(hash.charAt(j)));
                builder.append(bin);
            }
            for (int k = 0; k < builder.length(); k++) {
                a[i][k] = builder.charAt(k) - '0';
            }
        }
        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a[i].length; j++) {
                if (a[i][j] == 1) {
                    count++;
                    removeRegion(a, i, j);
                }
            }
        }

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