Longest Consecutive Sequence: Go Interview with a FAANG Engineer

A candidate works through three algorithmic problems in Go during a mock interview with a senior FAANG engineer. This mock touched on correctness, complexity tradeoffs, implementation clarity, and communication — the core signals real interviewers evaluate. 🧩 Problem 1 — Longest Consecutive Sequence (Unsorted Array) Design an O(n) solution using a hash set to identify sequence starts and expand. Covers duplicate handling, boundary detection, and correctness reasoning without sorting. 🧩 Problem 2 — Binary Tree Level Order Traversal Classic BFS over tree nodes, using a queue and level-by-level batching. Discussion includes space complexity, queue growth, and common implementation pitfalls. 🧩 Problem 3 — Cutting Trees on a Cliff (Grid Stability / Connectivity) After removing one tree, determine which remaining trees are still connected to the bottom row. Involves multi-source BFS/DFS from stable nodes, component tracking, and correctness guarantees for 4-directional connectivity. Key skills demonstrated • Translating verbal reasoning into clean Go implementations • Maintaining communication while coding (a major FAANG evaluation axis) • Applying BFS/DFS patterns across trees and grids • Identifying optimal vs. suboptimal approaches via time/space analysis • Handling interviewer hints and recalibrating solutions • Ensuring correctness through example-driven verification 👉 Book coaching or watch more mock interviews: https://www.interviewing.io 📝 Interview transcript & feedback: https://interviewing.io/mocks/faang-go-longest-consecutive-sequence 🔗 Explore more FAANG interviews: https://www.interviewing.io/mocks Disclaimer: All interviews are shared with explicit permission from the interviewer and interviewee. All candidates remain anonymous.