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private static String generateResultString(final List<Integer> digits) {

    final StringBuilder sb = new StringBuilder();
    assert digits.size() > 0;
    sb.append(digits.get(0));

    if (digits.size() > 1) {
        sb.append('.');
        for (final Iterator<Integer> itr = digits.listIterator(1); itr.hasNext();) {
            final int digit = itr.next().intValue();
            if (digit >= 0) {
                sb.append(digit);
            } else {
                int insertPoint = sb.length() + digit;
                if ('.' == sb.charAt(insertPoint)) {
                    insertPoint += 1;
                    sb.append(0);
                }
                sb.insert(insertPoint, '{');
                sb.append('}');
            }
        }
    }
    return sb.toString();
}