:orphan:

Multiply Strings
================

.. highlight:: none

Problem
-------
https://leetcode.com/problems/multiply-strings/

Given two non-negative integers ``num1`` and ``num2`` represented as
strings, return the product of ``num1`` and ``num2``, also represented
as a string.

**Note:** You must not use any built-in BigInteger library or convert
the inputs to integer directly.



**Example 1:**

::

   Input: num1 = "2", num2 = "3"
   Output: "6"

**Example 2:**

::

   Input: num1 = "123", num2 = "456"
   Output: "56088"



**Constraints:**

- ``1 <= num1.length, num2.length <= 200``
- ``num1`` and ``num2`` consist of digits only.
- Both ``num1`` and ``num2`` do not contain any leading zero, except
  the number ``0`` itself.

.. highlight:: python

Pattern
-------
Math, String

Approaches
----------

.. tab-set::

    .. tab-item:: Grade School

        **Code**

        .. literalinclude:: ../problems/medium/multiply-strings/multiply_strings__grade_school.py
            :language: python
            :lines: 14-

        **Test**

        >>> from multiply_strings__grade_school import multiply
        >>> multiply("2", "3")
        '6'
        >>> multiply("123", "456")
        '56088'
        >>> multiply("0", "0")
        '0'
        >>> multiply("999", "999")
        '998001'

        .. autofunction:: multiply_strings__grade_school.multiply