Problem 162. High school cafeteria

Created by the cyclist

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Given an input vector of positive integers, return a row vector with the primes first (in increasing order) and the composites next (also in increasing order).

The number 1 is neither prime nor composite. Put it with the composites for this problem.

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Last Solution submitted on Oct 24, 2025

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Alfonso Nieto-Castanon on 29 Jan 2012

need to add non-sorted test samples (e.g. [3,2,1])?

Tom Holz on 26 Feb 2013

It looks like 1 is being incorrectly sorted as a composite number in the testcases.

the cyclist on 27 Feb 2013

I somehow Alfonso's older comment until I saw Tom's newer one.

Alfonso: I've added a non-sorted test sample, and had the problem rescored.

Tom: 1 is neither prime nor composite. I've added instructions on how to handle that.

Ned Gulley on 20 Jun 2013

I had assumed that "in order" meant "in the order provided". If that were the case, then [5 1 3 2 4] would return [5 3 2 1 4]. Maybe you could say you want them sorted rather than in order.

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Problem 162. High school cafeteria

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Problem 162. High school cafeteria

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