题解 | Primary Arithmetic

#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>

using namespace std;

int add(vector<int>a, vector<int>b) {
    int t = 0;
    vector<int>c;
    int count = 0;
    for (int i = 0, j = 0; i <= a.size() || j < b.size() || t; i++, j++) {
        if (i < a.size())t += a[i];
        if (j < b.size())t += b[j];
        c.push_back(t % 10);
        t /= 10;
        if (t > 0)count++;
    }
    return count;
}
int main()
{
    string str1, str2;
    while (cin >> str1 >> str2) {
        if (str1 == "0" && str2 == "0")break;
        vector<int>a, b;
        for (int i = str1.size() - 1; i >= 0; i--)
            a.push_back(str1[i]-'0');
        for (int j = str2.size() - 1; j >= 0; j--)
            b.push_back(str2[j]-'0');
        int res = add(a, b);
        if (res == 1)
            printf("%d carry operation.\n", res);
        else if(res>1)
            printf("%d carry operations.\n", res);
        else
            printf("NO carry operation.\n");
    }

}