Add Binary Strings | Dataford Interview Questions

Veritas NetBackup may represent compact metadata values as binary strings. Given two non-empty strings a and b containing only '0' and '1', return their binary sum as a string.

Do not convert the entire inputs to decimal integers. Process the strings directly so the algorithm works efficiently for very large binary values.

Formal Specification

Implement add_binary(a, b), where a and b are binary strings. Return a binary string representing a + b, with no leading zeroes unless the result is exactly "0".

Constraints

1 <= len(a), len(b) <= 10^5
Each input contains only the characters '0' and '1'
Inputs may have different lengths
The result must not contain leading zeroes unless it is exactly "0"

Function Signature

def add_binary(a, b):

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