Find expected tosses to see a coin pattern
Company: Bnp
Role: Data Scientist
Category: Software Engineering Fundamentals
Difficulty: easy
Interview Round: Technical Screen
A fair coin is tossed repeatedly until a target length-3 pattern appears as a **consecutive** substring (e.g., HHH, HTH, HTT, etc.).
1) Describe a general method to compute the expected number of tosses to see a given pattern.
2) Compute the expected number of tosses for **HHH** and for **HTH**.
Overview: Assesses probabilistic reasoning and stochastic-process modeling skills, focusing on expected stopping times for pattern occurrences in repeated independent trials and related concepts like state-space representation and overlap effects.