Problem 46. Which doors are open?

Created by Cody Team

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Last Solution submitted on Sep 22, 2023

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Jan on 27 Jan 2012

The description does not match the example: The point 3 should be "3. On the # trip down the alley, start with door # [and process every #-th door]".

David Young on 3 Feb 2012

I agree with Jan - the description is not clear. The final instruction should be "return the list of open door #'s", presumably.

David Young on 3 Feb 2012

If the description was clearer, I'd give this problem a "like", because a good solution depends on a good analysis of the problem more than on just neat coding.

Ned Gulley on 1 Mar 2012

Sorry about the confusion. I tried to clarify the problem description.

Mattias on 4 Jan 2015

Nice problem! The explicit solution was very surprising to me once I found it.

Michael on 9 Feb 2015

Classic problem--unfortunate that the test suite reveals the punchline.

Justin Pinkney on 28 Jan 2016

Yes I initially thought y = sum(open doors)

Jerivington on 2 Jun 2016

good problem, easy solution once realising how to solve

Sanzhar Askaruly on 17 Jun 2019

easy if to think a bit

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Problem 46. Which doors are open?

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