题解 | 大数加法

class Solution {
public:
    string solve(string s, string t) {
        int n1 = s.size();
        int n2 = t.size();
        if(n1<n2)
            s = std::string(n2-n1, '0') + s;
        else if(n1>n2)
            t = std::string(n1-n2, '0') + t;

        int jinwei = 0;
        int n = max(n1, n2);
        int curr = 0;
        string res = "";
        for(int i=n-1; i>=0; i--){
            curr = s[i]-'0' + t[i]-'0' + jinwei;
            jinwei = curr / 10;
            curr %= 10;
            res = char(curr+'0') + res;
        }

        if(jinwei)
            res = char(jinwei+'0') + res;

        return res;
    }
};

为了能够更简单地相加，首先可以对齐二者长度，短的那个前面补‘0’即可。