Problem 690. Remove the two elements next to NaN value

Created by Aurelien Queffurust

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The aim is to remove the two elements next to NaN values inside a vector.

For example:

 x = [6 10 5 8 9 NaN 23 9 7 3 21 43 NaN 4 6 7 8]

The output y will be:

 y = [6 10 5 8 9 7 3 21 43 7 8]

Nan values and the 2 next elements after the NaN (23-9 and 4-6) have been removed.

There will be always NaN values in the input vector followed by at least 2 integers.

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Last Solution submitted on Apr 27, 2025

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@bmtran (Bryant Tran) on 16 May 2012

i think the question may be worded incorrectly. there is no adding

Aurelien Queffurust on 16 May 2012

Exact . Thanks for the remark , I replaced the "add" word by "remove"

Justin Fritz on 3 Aug 2017

Problem name “Remove the two elements next to NaN value” is confusing. In a 1d array the first and last element have 1 element next to them while other elements have 2 elements next to them. The name would imply that we are to remove one element preceding and one element following a NaN however in the problem description we are told to remove the two elements following the NaN. I would argue that the element preceding the NaN is more “next to” the NaN than the element two elements away. Name should be changed to “Remove the two elements following a NaN value”.

Li Ding on 20 Oct 2017

The term "next to NaN" would generally be considered as the one right before and the one right after NaN, if existing. Also the problem failed to say that NaN themselves need to be removed.

David Verrelli on 12 Jan 2018

JF & LD, I agree with both of your comments. Furthermore, it is unfortunate that in the example the first NaN has digit "9" both immediately preceding it and two elements after it, making the procedure to get the result in that neighbourhood ambiguous.

Israt Jahan on 20 Jun 2020

not so easy problem. Took a lot of time for thinking!

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Problem 690. Remove the two elements next to NaN value

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Problem 690. Remove the two elements next to NaN value

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