Arrays 2

multiply two arbitary precision arrays

/*Program to multiply two arbitary precision arrays */

vector<int> Multiply (vector<int> num1, vector<int> num2)
{
    // The result will be sum of size of 2 numbers + 1. setting it to 0 initially
    vector result(num1.size()+num2.size()+1,0);

    //Return early if either is empty
    if(num1.empty() || num2.empty())
        return result;

    // check signs and take absolute values of the numbers
    bool sign = (num1.front()<0 && num2.front()>0 )||(num1.front()>0);
    num1.front() = abs(num1.front());
    num2.front() = abs(num2.front());

    // We perform standard partial multiplication

    for (int i = num1.size(); i>0; i--)
    {
        for (int j = num2.size(); j>0; j--)
        {
            result[i+j+1] += num1[i]*num2[j];
            result[i+j] =  result[i+j+1]/10;
            result[i+j+1] = result[i+j+1]%10;
        }
    }

    if (sign)
        result.front()*= -1;

    return result;
}