Sum of Very Large Integers | Dataford Interview Questions

Wayfair pricing and promotion services may need to combine values represented as strings when the numbers exceed native integer limits. Given two integer strings, return their exact sum without converting either complete input to an integer type.

Formal Specification

Implement add_strings(num1, num2), where both inputs are non-empty strings representing signed decimal integers. An optional leading - is allowed. Positive signs are not included. Inputs may contain leading zeros. Return a string containing the canonical decimal representation of the sum, with no leading zeros unless the result is zero.

Your algorithm must perform arithmetic manually, digit by digit. Do not use Python's int, arbitrary-precision integer conversion, floating-point arithmetic, or equivalent libraries on the complete inputs.

Constraints

1 <= len(num1), len(num2) <= 1,000,000
Each input contains decimal digits and may begin with one '-'.
Inputs may contain leading zeros.
The result must be returned in canonical decimal form.
Do not convert either complete input to a numeric type.

Function Signature

def add_strings(num1, num2):

Your question is Sum of Very Large Integers. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Formal Specification

Constraints

1 <= len(num1), len(num2) <= 1,000,000
Each input contains decimal digits and may begin with one '-'.
Inputs may contain leading zeros.
The result must be returned in canonical decimal form.
Do not convert either complete input to a numeric type.

Function Signature

def add_strings(num1, num2):

Your question is Sum of Very Large Integers. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.