大数加法模板

计算 a + b

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

string sol;

void solve(string a, string b){
    int j = b.size() - 1, i = a.size() - 1, cnt = 0;
    for(; i >= 0 && j >= 0; i--, j--){
        int x = a[i] - '0';
        int y = b[j] - '0';
        sol += (char)((x + y + cnt) % 10 + '0');
        cnt = (x + y + cnt) / 10;
    }
    while(i >= 0){
        int x = a[i--] - '0';
        sol += (char)((x + cnt) % 10 + '0');
        cnt = (x + cnt) / 10;
    }
    while(j >= 0){
        int y = b[j--] - '0';
        sol += (char)((y + cnt) % 10 + '0');
        cnt = (y + cnt) / 10;
    }
    if(cnt) sol += '1';
    reverse(sol.begin(), sol.end());
}

int main(void){
    string a, b;
    cin >> a >> b;
    solve(a, b);
    cout << sol << endl;
    return 0;
}