Multiply Numeric Strings | Dataford Interview Questions

Nuro's onboard software may receive numeric values that exceed the range of native integer types. Given two signed decimal integers as strings, return their exact product as a normalized decimal string.

Do not convert either input to a native integer or use a library routine that performs the entire multiplication. Implement the grade-school multiplication algorithm using digit operations.

Formal Specification

Implement multiply_strings(a, b), where a and b are strings matching the format [+-]?\d+. Return a string containing the product with no unnecessary leading zeroes, except that zero must be returned as "0". A leading plus sign is not included in the output.

Constraints

1 <= len(a), len(b) <= 10^4
Each input matches the format [+-]?\d+
Inputs may contain leading zeroes
Return a normalized decimal string
Do not convert the complete inputs to native integers

Function Signature

def multiply_strings(a, b):

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