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If you have a question to do with entering the APL Problem Solving Competition, and the answer is not given on this page, then please send an e-mail to

Frequently Asked Questions

What prizes could I win?

The winners will receive a cash prize of $2,500 for first prize, $1,250 for second prize and $750 for third prize. The top ten (10) Phase I submissions will each be awarded prizes of $100.

The first prize winner will also be invited to attend the next annual Dyalog user meeting to receive the prize in person and present the work that led to winning the grand prize. Dyalog will pay travel costs (up to $3,500), plus $500 for incidental expenses and all user meeting fees. The winning student is responsible for visas, travel documents and other necessary arrangements and must be legally able to travel. Only costs for the winner will be provided.

Ten (10) $100 prizes will be awarded to eligible Phase I participants.

Five (5) $200 prizes will be randomly awarded to eligible participants who submit a correct answer to any question set in Phase II.

One (1) non-student winner will win a package covering their Dyalog user meeting registration fee and accommodation. The winning non-student winner is responsible for visas, travel documents and other necessary arrangements and must be legally able to travel.

Only students that can prove student-status are eligible to win the cash prizes.

Who is eligible to participate?

This contest is open to everyone (except contest organisers and employees of Dyalog Ltd.). However, to be eligible for any of the cash prizes you must be a full time student at any primary or secondary school, college or graduate university and able to submit proof of full-time enrolment in a school or a university. You can be on a sabbatical as long as you will be returning to full-time student status within a year.

Non-students are welcome to submit solutions, but only students that can prove enrolment are eligible for the cash prizes.

Identical submissions

If multiple people make nearly identical submissions, all of them will be disqualified.

How will prizes be paid?

All prizes are denominated in U.S. dollars. They can be awarded:

  • by electronic transfer to a bank account (in U.S. dollars, pounds sterling or euros)
  • by electronic transfer to a PayPal account (in U.S. dollars, pounds sterling or euros)

No other forms of payment will be made.

How do I win?

To win one of the cash prizes you must complete the 10 simple problems in Phase I and at least a minimum set of solutions to Phase II.

We will accept any APL code that can be loaded and run by a Microsoft Windows, macOS, or Linux Dyalog Interpreter, version 13.0 or later.

The submission format is a UTF-8 text file describing a Dyalog namespace that contains a sub-namespace for each problem which has been solved. A valid example of the file format can be downloaded from (link). You can, therefore, use any APL interpreter to develop your code as long as the code that you submit runs under Dyalog APL and you are able to generate the required UTF-8 file containing your submission.

What is an acceptable solution?

Your solution must be unique. If your solution is identical to, or substantially similar to, any other entrants' solutions, then none of you will receive credit for the solution. This is tricky because, for many problems, the solution that occurs to most APL programmers will be similar. However, you can make your submission unique by adding comments in your own words that make it clear that you understand what the code does.

I am not a student. Can I submit answers?

Definitely! We encourage non-students to try the problems and submit solutions. Although you won't be eligible for any of the cash prizes, you can still win an invitation and accommodation for the annual Dyalog user meeting.

How do I make a submission?


I don't know any APL. What am I supposed to do?

That's the point of this contest, to get you to learn about this stuff. You might want to start by investigating Bernard Legrand's Mastering Dyalog APL.

Can I collaborate with others?

Yes. However, each contest submission must be made by a single individual and only that individual will be eligible for a prize. If you chose to share your winnings with other people, then you must make your own arrangements. If you win the Grand Prize, then you can choose to send a collaborator to the user meeting in your place but that person is expected to be able to present the work competently.

If you collaborate with others in learning APL and solving the problems, you are permitted to make separate entries as long as your code is not identical and you have individual Dyalog educational licences.

Where do I submit questions about the contest?

You can e-mail your questions to We don't guarantee that we will answer them, but if we do we are most likely to add your question and the answer to this page – check back frequently for updates, clarifications, and so on.

Can I appeal the results?

No. The judges' decisions are final.

Does it matter when I submit my entry as long as it's before the deadline?

No. Submissions are not judged until after the deadline has been reached.

Is there a way to write loops, or should I write pseudo-loops using recursion? Is execution order guaranteed in (for example) 'each', and should I exploit that?

You are expected to find the answers to all APL-specific questions yourself!

Can I utilise functions or code snippets from the workspaces that come with Dyalog (for example, dfns) or other sources?

Yes. However, you will be judged both on the uniqueness of your code and evidence of your understanding of what you are doing. The judges read the Dyalog Forums (and other similar channels) and will notice if contestants are asking for too much help. So, at a minimum, include comments (in your own words) indicating that you understand what it is doing – don't just copy someone else's comments along with their code. If you really want to score well, you might want to see if you can improve on the code you find elsewhere. What's more, if you are in the running for a top prize, then the judges might contact you to discuss your entry. Be prepared to talk about it intelligently.

Can I use a Dyalog Educational or Non-Commercial Licence to enter this competition or does the possibility of winning prize money classify this as commercial use of the product?

Dyalog Ltd. does not consider participation in this programming contest to be a violation of the terms of these licences – it is, therefore, legal to use either of these licences to create your contest entry.

Why will the system not let me finalize my submission?

In case of a technical error, please report the problem to

I am having difficulty loading the page. I think it may be a browser issue. What are the recommended browsers to enter the challenge?

The latest versions of Chrome, Firefox and Safari, or Internet Explorer 10.

I did not receive a confirmation email after signing up for the competition. What should I do?

If you did not receive a confirmation email within 5-10 minutes, try checking your spam box. Otherwise, please report the problem to

What if my school/university name is not listed?

If the name of your school/university is not listed, please inform us by email at