模拟

class Solution {
public:
    string solve(string s, string t) {
        int len1 = s.size();
        int len2 = t.size();
        reverse(s.begin(), s.end());
        reverse(t.begin(), t.end());
        vector<int> v(max(len1, len2)+10, 0);
        for (int i = 0; i < max(len1, len2); i++)
        {
            if (i < len1)
            {
                v[i] += s[i]-'0';
            }
            if (i < len2)
            {
                v[i] += t[i]-'0';
            }
        }
        int temp = 0;
        for (int i = 0; i < v.size(); i++)
        {
            v[i] += temp;
            temp = v[i] / 10;
            v[i] %= 10;
        }
        int f = 0;
        string ans;
        for (int i = v.size() - 1; i >= 0; i--)
        {
            if (f == 0 && v[i] == 0)
                continue;
            f = 1;
            ans.push_back(v[i] + '0');
        }
        if (!ans.size())
            return "0";
        return ans;

    }
};