Happy Neighborhood

Problem Overview

• Determine the first day the neighborhood becomes happy: when at least one block of M consecutive houses is occupied.
• Input: N houses, M target adjacency, and house[1..N] permutation giving the house occupied each day; Output: earliest day index.
• Context: residents move into a linear street; happiness occurs with a contiguous occupied segment.
• Source: Asked in Google interviews; a classic coding interview problem and interview question.