题解 | 高精度整数加法

#include <iostream>
#include <algorithm>
using namespace std;

int stringNumAdd(char a, char b, string& s, int num = 0) {
    int n = isspace(a) ? 0 : a - '0';
    int m = isspace(b) ? 0 : b - '0';
    int sum = n + m + num;
    int overflow_num = sum > 9 ? 1 : 0;

    //cout << (sum % 10);
    s += to_string(sum % 10);

    return overflow_num;

}

int main() {
    string s1, s2;

    while (cin >> s1 >> s2) {
        int n = s1.size();
        int m = s2.size();
        int length = max(n, m);
        int num = 0;
        reverse(s1.begin(), s1.end());
        reverse(s2.begin(), s2.end());
        string str = "";
        for (int i = 0; i < length; i++) {
            char a = i < n ? s1[i] : ' ';
            char b = i < m ? s2[i] : ' ';
            num = stringNumAdd(a, b, str, num);

            if ((i == length - 1) && num > 0)
	            str = str + "1";
        }
        reverse(str.begin(), str.end());

        cout << str << endl;
    }


    return 0;
}