133. Multiply Strings

Medium · String

Multiply two non-negative integers represented as strings, and return their product as a string. You cannot convert the entire strings to numbers using built-in functions like parseInt or BigInt — you must implement multiplication yourself, similar to how you'd multiply by hand. The input is an array [num1, num2] where each element is a string of digits. Return the product as a string with no leading zeros (except for the result "0" itself).

Examples

Example 1
Input: ["2", "3"]
Output: "6"
Explanation: 2 × 3 = 6
Example 2
Input: ["123", "456"]
Output: "56088"
Explanation: 123 × 456 = 56088

Constraints