Compute expected coin flips to meet on octagon
Company: Optiver
Role: Data Scientist
Category: Statistics & Math
Difficulty: medium
Interview Round: Technical Screen
Two independent particles start at opposite vertices (four edges apart) of a regular octagon. At each time step, flip one fair coin for each particle: heads moves one step clockwise, tails one step counterclockwise. What is the expected total number of coin flips required until the two particles occupy the same vertex?
Quick Answer: Compute expected coin flips to meet on octagon evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.