Building an Iterator Protocol

Medium Design Patterns & Final Challenges

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Problem Statement

Create a `Countdown` class that implements Python’s strict iterator protocol using `__iter__` and `__next__`. It should count down from a `start` value to 0. Read an integer, instantiate the iterator, and loop through it, printing each number separated by spaces.

Input Format

A single integer N.

Output Format

Print space-separated countdown sequence.

Constraints

N >= 0

Sample Input

Sample Output

3 2 1 0

Explanation

Custom objects can integrate directly into standard `for` loops by defining iteration protocols and raising `StopIteration`.

Starter Code

class Countdown:
    # Implement __init__, __iter__, and __next__
    pass

if __name__ == '__main__':
    n = int(input().strip())
    # Instantiate and iterate
    pass

Limits

Time Limit: 1s
Memory Limit: 256MB

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