# 43 Multiply Strings

Given two numbers represented as strings, return multiplication of the numbers as a string.

Note:

```
The numbers can be arbitrarily large and are non-negative.
Converting the input string to integer is NOT allowed.
You should NOT use internal library such as BigInteger.
```

* Algorithm:
  * Store into vector of digits using itoa

```cpp
string multiply(string num1, string num2) {

}
```