43. Multiply Strings

<span style="font-size:18px;">string multiply(string num1, string num2) {
if (num1 == "0" || num2 == "0") return "0";
int sa = num1.size();
int sb = num2.size();
vector<int> temp(sa + sb, 0);
for (int i = sa - 1; i >= 0; i--) {
int a = num1[i] - '0';
for (int j = sb - 1; j >= 0; j--) {
int b = num2[j] - '0';
int product = a*b;
int carry = (temp[j + i + 1] + product) / 10;
temp[j + i + 1] = (temp[j + i + 1]+product) % 10;
int x = 0;
while (carry) {
int p = temp[j + i - x] + carry;
temp[j + i - x] = p % 10;
carry = p / 10;
x++;
}
}
}
while (temp[0] == 0) temp.erase(temp.begin());
string res;
for (int i = 0; i < temp.size(); i++) {
res += to_string(temp[i]);
}
return res;
}</span>