Swap Parity

Problem Overview

• Rearrange a numeric string by swapping adjacent digits only when both have the same parity (both odd or both even) to form the largest possible number.
• Input: string num (digits 0–9), length 1–1e5. Output: largest number as a string.
• Domain: string manipulation and parity-based digit grouping in number formatting.
• Palantir interview question; a coding interview problem for constraint-heavy reasoning.