How do you split coins to match heads?
Company: Bnp
Role: Data Scientist
Category: Software Engineering Fundamentals
Difficulty: easy
Interview Round: Technical Screen
There are **N** coins on a table. You are told that exactly **H** of them are heads-up (you do not know which ones). You must split the coins into **two piles** so that the **number of heads-up coins is the same in both piles**. You are allowed to flip any coins you choose.
Describe a strategy that always works and justify why it works.
Overview: This question evaluates logical reasoning about invariants and combinatorial parity, testing the candidate's ability to design deterministic strategies under partial information; it falls under Software Engineering Fundamentals with relevance to probability and discrete mathematics for a Data Scientist role.