[LeetCode]Plus One

Given a number represented as an array of digits, plus one to the number.

思考：大数相加的思想。flag是进位标记。

class Solution {
public:
    vector<int> plusOne(vector<int> &digits) {
        int len=digits.size();
        bool flag=false;
        digits[len-1]+=1;
        int i=len-1;
        if(digits[i]>9) flag=true;
        while(flag&&i>0)
        {
            digits[i]=digits[i]%10;
            digits[i-1]+=1;
            if(digits[i-1]>9) flag=true;
            else flag=false;
            i--;
        }
        if(digits[0]>9)
        {
            digits[0]=digits[0]%10;
            vector<int> ans;
            ans.push_back(1);
            for(i=0;i<len;i++)
            {
                ans.push_back(digits[i]);
            }
            return ans;
        }
        return digits;
    }
};