Envío 2895

Código

#include <iostream>

using namespace std;

int cast(char c) {
    return (c - '0');
}

string big_sum(string x, int i, string y, int j)
{
    int carry = 0, sum = 0, unit = 0;
    for (; i >= 0; --i, --j)
    {
        sum = (j >= 0) ? cast(x[i]) + cast(y[j]) : cast(x[i]);
        sum += carry;
        unit = sum % 10;
        x[i] = unit + 48;
        carry = (sum > 9) ? 1 : 0;
    }
    if ((i < 0 && carry == 1) || (x[0] == '0' && carry == 1))
        return '1' + x;
    else
        return x;
}

int main(void)
{
    string x, y;
    cin >> x;
    cin >> y;

    int i = x.length() - 1, j = y.length() - 1;
    string res = (i > j) ? big_sum(x, i, y, j) : big_sum(y, j, x, i);
    cout << res << endl;

    return (0);
}