66 加一

https://leetcode.cn/leetbook/read/top-interview-questions-easy/x2cv1c/

https://leetcode.cn/problems/plus-one/description/

cost: 5m49s

class Solution {
public:
    vector<int> plusOne(vector<int>& digits) {
        vector<int> r = {};
        int delta = 1;
        for (int i = digits.size() - 1; i >= 0; i--) {
            int v = digits[i] + delta;
            delta = v / 10;
            r.push_back(v % 10);
        }
        if (delta > 0) {
            r.push_back(delta);
        }
        for (int i = 0, j = r.size() - 1; i < j; i++, j--) {
            int tmp = r[i];
            r[i] = r[j];
            r[j] = tmp;
        }
        return r;
    }
};

• 时间复杂度：O(n)
• 空间复杂度：O(1)