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user@intervues:~/experiences/…$
Level: Senior-Level
Round: Onsite · Type: Multiple Types · Difficulty: 6/10 · Duration: 180 min · Interviewer: Neutral
Topics: Data Structures, Algorithms, System Design
Location: San Francisco Bay Area
Interview date: 2026-01-15
Got offer: False
Question: I was asked to implement a SensorHealth class to determine if a sensor is STABLE or UNSTABLE based on ping signals within a time window.
Question: I had to determine if there's a valid order to load/unload items such that the robot's load equals a TargetWeight at some point.
Question: I was asked to design a temporary email service for 100M active users.
Coding Question 1: The "Silent Sensor" Detector
Problem: You are monitoring a network of IoT sensors that send intermittent "ping" signals. You possess a log of these pings, where each entry consists of SensorID : A string (e.g., "Sensor_Alpha", "Sensor_Beta"), Timestamp: An integer representing the time of the ping. Implement a class SensorHealth that determines if a sensor is STABLE or UNSTABLE relative to a specific query time T.
To check the status at time T, look at a fixed monitoring window starting at T consisting of 5 sequential time slots, each 60 seconds long (total window = 300 seconds). Slot 1: [T, T + 59] Slot 2: [T + 60, T + 119] ...and so on up to Slot 5. A slot is considered "Active" if it contains at least one ping for that SensorID. A sensor is UNSTABLE if, within this 5-slot window, there are 3 consecutive "Inactive" slots. Otherwise, the sensor is STABLE.
Coding Question 2: The Warehouse Loading Problem
Problem: You are managing a loading dock robot. You are given a list of N items with integer weights W (positive weights represent loading an item, negative weights represent unloading/removing an item). The robot starts with a load of 0. You do not know the order in which the robot processed these items. Determine if there exists any valid ordering of these N operations such that the robot's total load equaled exactly TargetWeight at any point during the process.
System Design Question
Problem: Design a temporary email service that supports 100M active users