Unread Notification Badge Counter

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Your question is Unread Notification Badge Counter. Start with the requirements on the right.

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Problem

Given a list of notification events for a mobile app, return the unread badge count after processing all events. Each event is a list where the first value is the event type: "receive", "read", or "clear". A receive event adds a notification with a unique integer id, a read event marks that id as read if it exists and is unread, and a clear event removes all unread notifications. Return the final unread count as an integer.

Constraints

1 <= len(events) <= 10^5
For receive and read, event format is [type, id] where 0 <= id <= 10^9
For clear, event format is ["clear"]
Notification ids are unique across receive events

Function Signature

def unread_badge_count(events):

Your solutionPython 3

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