Implement the Observer Pattern

Medium Design Patterns & Final Challenges

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Problem Statement

Create a `Subject` class that allows `Observer` objects to `attach()`. When `Subject.set_state(state)` is called, it triggers `update(state)` on all attached observers. Read a state string, attach two observers (Obs 1 and Obs 2), update the subject, and print the notifications.

Input Format

A single string representing the state.

Output Format

Print the observer notifications.

Constraints

None

Sample Input

Ready

Sample Output

Obs 1: Ready
Obs 2: Ready

Explanation

The Observer pattern lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they're observing.

Starter Code

class Subject:
    pass

class Observer:
    pass

if __name__ == '__main__':
    state_input = input().strip()
    # Implement observer logic
    pass

Limits

Time Limit: 1s
Memory Limit: 256MB

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