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Proposed Release Schedule for New Problems

  • Problem 690 is scheduled for Sunday, 24th November 2019, 07:00 am
  • Problem 691 is scheduled for Sunday, 1st December 2019, 10:00 am
  • Problem 692 is scheduled for Saturday, 7th December 2019, 01:00 pm
  • Problem 693 is scheduled for Saturday, 14th December 2019, 04:00 pm
  • Problem 694 is scheduled for Saturday, 21st December 2019, 07:00 pm
  • Problem 695 is scheduled for Saturday, 28th December 2019, 10:00 pm
  • Problem 696 is scheduled for Sunday, 5th January 2020, 01:00 am

Recent News

14 October 2019: Maintenance Notice

On Tuesday evening 15 October 2019 (UK time), Project Euler will be inaccessible for maintenance due to an internal migration to a new VPS. Although we have been happy with the general performance on the current server, by moving to a more powerful server we are hoping that this will provide a stable environment for quite some time to come.

After the DB migration and testing has been completed it will be necessary to update the DNS on the VPS cluster. For most people this should happen quickly, but fully propagating throughout the global network means that some members may have to wait longer. Whilst your local DNS has not been updated you will continue to point at the old server, which will remain in maintenance status. So as soon as Project Euler appears to be back online you will know that your DNS has been updated; you will be on the new server and able to continue solving problems. Due to the way we are handling this there should be no data loss.

Whilst the main website is inaccessible we would remind you that a static version of the problems can be found at https://projecteuler.info. The problem set is up-to-date and although it will not update your profile, you are able to check answers. This link will appear on the maintenance notice page when it appears.

We hope that the move goes smoothly, but we would ask for your patience and understanding if we encounter any issues.

25 August 2019: DB Migration Issue

To keep the website running optimally it becomes necessary for our hosts to periodically migrate the DB to a new server. We are very grateful for their diligence in this matter and it has always happened in the past without incident. However, today it seems that some of the data on the new server became corrupt during the transfer. Consequently it was impossible to sign-in, giving the impression that your account no longer existed. Fortunately, all the data remained intact on the old server.

So once the issue had been reported our hosts were able to point the site back to the DB on the old server before carefully ensuring that all of the data was migrated properly this time.

We are very sorry for the inconvenience and the scare this might have caused some members when they thought for a moment that their accounts had disappeared.

The site is now pointing at the DB on the new server and it should all be working as expected. It is highly unlikely that any data has been lost during the migration, but if you solved any problems in the last day, then for your own peace of mind it is recommended that you check no progress has been lost.

20 August 2019: Pinning Problems

A change was made recently to the website that allows you to pin problems. This should be useful if you wish to return to a particular problem.

At the top of each problem page you will find a small icon in the top right corner allowing you toggle between pin/unpin. Once a problem is pinned the ID will appear in blue on the problems table page and it will be shaded blue on your Progress page. In addition, on the Archives page you can also filter problems by pinned. Please note that currently each member is limited to ten pins.

Hopefully this proves to be a useful addition to Project Euler. If you spot any issues, then please use the thread:
https://projecteuler.chat/viewtopic.php?f=5&t=6947

17 June 2019: Summer Break

Problem 677 on Saturday 29th June will be the last problem of this season. Project Euler will then take a summer break, returning with a new problem on Saturday 7th September.

3 March 2019: Style Sheet Update

As technology has evolved it seems that Project Euler has taken time to catch-up. A common request in recent years has been to modify the style sheets to be make the website mobile device friendly. This includes a responsive framework that should dynamically adapt the display to accommodate a variety of screen widths.

It has taken a lot of work, given the regimented tabular structure of many pages, but we are pleased to reveal the fruits of that labour.

This has required significant changes not only to the style sheets, but the way in which the scripts dynamically produce pages. Extensive testing has been made, but as you can imagine there are going to be some setups that had not been anticipated and consequently pages may not render as expected. In addition, as part of the the process a number of decisions have been made to modernise the style sheets, including the use of CSS variables to simplify future changes. Whereas support for this has been in place in all of the main browsers for several years now, it does mean that some old browsers may suffer. Special provision has been made to provide legacy CSS support for Internet Explorer, which means that IE will only render a version of the default theme .

If you notice any specific issues, then we would ask you to report them at the following address on our alternative forum.
https://projecteuler.chat/viewtopic.php?f=5&t=6873

For many members they will notice nothing more than, what we hope, a cleaner more pleasing appearance. For mobile device users we hope that the effort was worth it and navigating the site becomes an enjoyable experience.