Plus One

c++

class Solution {public:    vector<int> plusOne(vector<int>& digits) {        if (digits.empty())            return digits;        int update = 0;        int n = digits.size() - 1;        while (n>=0){            if (n == digits.size() - 1)                update += digits[n] + 1;            else                update += digits[n];            digits[n] = update % 10;            update /= 10;            n--;        }        if (update > 0){            digits.insert(digits.begin(), update);        }        return digits;    }};

python

class Solution(object):    def plusOne(self, digits):        """        :type digits: List[int]        :rtype: List[int]        """        if not digits: return digits        update = 0        n = len(digits)-1        while n>=0:            if n== len(digits)-1:                update += digits[n]+1            else:                update += digits[n]            digits[n] = update%10            update /= 10            n -= 1        if update >0:            return [1] + digits        return digits