## Round 1 - Coding ## Problem You are given a list of events. Each event is either `"START"` or `"END"`. A trip begins on a `START` event and ends on the next `END` event. Implement a `TripCounter` class that processes events one at a time and returns the number of completed trips at any point. ```python class TripCounter: def __init__(self): pass def process(self, event: str) -> int: # Returns total completed trips after processing this event pass def active_trips(self) -> int: # Returns number of currently open (unfinished) trips pass ``` ## Example ``` events = ["START", "START", "END", "END", "START", "END"] After "START" -> completed=0, active=1 After "START" -> completed=0, active=2 After "END" -> completed=1, active=1 After "END" -> completed=2, active=0 After "START" -> completed=2, active=1 After "END" -> completed=3, active=0 ``` ## Follow-ups 1. What if events include a trip ID and you need to match START/END by ID? How does your data structure change? 2. How would you handle an `END` event with no matching `START`? Should it throw, return -1, or be silently ignored? 3. If trips have timestamps, how do you compute average trip duration? 4. At scale (millions of events/sec), how would you process this in a distributed stream?

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Trip Counter - Tracking Active Journeys with Start/End Events

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Round 1 - Coding Problem You are given a list of events. Each event is either "START" or "END". A trip begins on a START event and ends on the next END event. Implement a TripCounter class that processes events one at a time and returns the number of completed trips at any point. Example Follow-ups What if events include a trip ID and you need to match START/END by ID? How does your data structure change? How would you handle an END event with no matching START? Should it throw, return -1, or be…

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Trip Counter - Tracking Active Journeys with Start/End Events

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