LeetCode – Refresh – Plus One

Assign a new vector as the size is length + 1. Because if the original is 9999...., the it will have one digit more.

class Solution {
public:
    vector<int> plusOne(vector<int> &digits) {
        int len = digits.size(), carry = 0;
        if (digits.size() == 0) return vector<int> ();
        vector<int> result(len+1, 0);
        digits[len-1]++;
        for (int i = len-1; i >= 0; i--) {
            result[i+1] = digits[i] + carry;
            carry = result[i+1]/10;
            result[i+1] %= 10;
        }
        if (carry) result[0] = 1;
        else result.erase(result.begin());
        return result;
    }
};