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.

You must not convert the inputs to integers directly or use any built-in big integer library.

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Example 1

Input: num1 = "2", num2 = "3"
Output: "6"
Explanation: 2 * 3 = 6.

Example 2

Input: num1 = "123", num2 = "456"
Output: "56088"
Explanation: 123 * 456 = 56088, computed digit by digit as in long multiplication.

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Constraints

• 1 <= num1.length, num2.length <= 200
• num1 and num2 consist of digits only.
• Both num1 and num2 do not have any leading zeros, except the number zero itself.