原题链接: https://oj.leetcode.com/problems/plus-one/

public byte[] plusOne(byte[] num) {
    if (num == null || num.length == 0) {
        return num;
    }

    byte[] result = num.clone();
    int length = num.length;

    for (int i = length - 1; i >= 0; i--) {
        byte digit = result[i];
        result[i] = (byte) (digit + 1);

        if (result[i] < 10) {
            break;
        } else {
            result[i] = 0;

            if (i == 0) {

                byte[] expandedNum = new byte[length + 1];
                expandedNum[0] = 1;

                return expandedNum;
            }
        }
    }

    return result;
}