IEEEXtreme 15.0 Call for Judges / Problem Authors

Are you fascinated by programming? We, the IEEEXtreme 15.0 Executive Committee, are opening the registrations for a select few judges and problem authors.

IEEEXtreme is a global challenge in which teams of IEEE student members compete in a 24-hour time span against each other to solve a set of programming problems authored by industry professionals and coding experts like yourself. Over the 15 years since it began, the competition has attracted over 70,000 competitors from over 2,500 schools in 90 countries around the world.

This is an opportunity where you can not only develop the coding challenges but also you can evaluate them while having the opportunity to associate with some of the top experts in the field. The judging staff of IEEEXtreme are all volunteers who strive to make the contest a fun and exciting experience for all.

Judges responsibilities may include one or more of the following:

Develop at least 1 original and innovative problem. You may see examples of the format of the IEEEXtreme problems here:
Review and evaluate the problems proposed by another judge and provide feedback;
Provide independent solutions to other proposed problems using any of the competition programming languages;
Be online during the day of the competition for 1-2 hours based on their availability in order to address the contestants’ questions related to the authored challenge.

While not everyone who submits a nomination will be selected, we will carefully review all nominations and thank you in advance for your time to express your interest! We look forward to welcoming you aboard to the IEEEXtreme community!

Please apply using this form on or before 2021/09/19.

More delineations can be acquired from: [email protected]

Ubuntu – Overwrite dockerd default settings

Trying to create a new bridge on docker, we got the following error

$ docker-compose up -d;
Creating network "docker-compose_new_bridge" with driver "bridge"
ERROR: could not find an available, non-overlapping IPv4 address pool among the defaults to assign to the network

After investigating, we realized that it was due to some default limitations of docker that did not allow more virtual networks to be created. To overcome the problem, we read that we had to give access to more address space using the /etc/docker/daemon.json.

On Ubuntu that file did not exist so we created it and copied the following content to it:

  "default-address-pools": [
      "base": "",
      "size": 24
      "base": "",
      "size": 24


This configuration allowed Docker to reserve the network address space 172.80.[0-255].0/24 and 172.90.[0-255].0/24, that provided the daemon a total of 512 networks each owning 256 addresses.

To apply the changes to the daemon, we restarted it:

sudo systemctl restart docker.service;

and then we applied our changes to our docker ecosystem:

docker-compose up -d;

Gaming with PlayStation Controllers of Android

Recently we decided to try and game on Android (specifically on a OnePlus 6T) using the controllers of Sony Playstation (Sony DualShock 4 wireless controller and Sony Dualsense wireless controller).

Sony DualShock 4 wireless controller

To use the Sony DualShock 4 wireless controller (, we paired the device using Bluetooth technology. To do so, we pressed the PlayStation logo button and the Share button to set the controller into pairing mode. Then, from our Android device, we paired the new device that appeared to have the name Wireless Controller.

We tried to play the game of Doom which worked like a charm! We had all functionality and the button mapping seemed very convenient.

Sony Dualsense wireless controller

To use the Sony Dualsense wireless controller (, we paired the device using Bluetooth technology again. To do so, we pressed the PlayStation logo button and the Create button to set the controller into pairing mode. Then, from our Android device, we paired the new device that appeared to have the name Wireless Controller.

To our disappointment, when we loaded the game of Doom we realized that the button mapping was very weird and not functional. The Slayer would spin all the time (you could prevent it by spinning in the other direction) and there was no button mapped to firing.


Sony DualShock 4 wireless controller worked like a charm on Android while Sony Dualsense wireless controller had some weird button mapping configuration making it unusable to play.

More results

After some additional investigation, we post the following:
We could not get the Dualsense controller to work as expected on any version of Android.
On the other hand, the Dualshock controller worked correctly on the following configurations:

  • OnePlus 6T + Android version 11
  • Samsung Galaxy S9 + Android version 9
  • Samsung Galaxy S9 + Android version 10

The Sony Dualshock controller failed as well on the following setup

  • Samsung Galaxy S9 + Android version 8

From these results, we can assume something was created or fixed in Android 9 and higher that allows Sony Dualshock wireless controller to work properly on Android devices.

Ubuntu how clear journal logs and free up some disk space

On a machine that has Ubuntu 20.04LTS was recently running out of space, while using the Disk Usage Analysis tool we noticed that /var/log/journal was taking a bit more than 4 GB.

We knew that the machine was not hosting any kind of public service nor did it have any hardware problems, so we decided to clear up old logs. To do so, we used the following command that removed all logs that were older than two days.

sudo journalctl --vacuum-time=2d;

The result was great as it saved 3.9 GB of space:

Vacuuming done, freed 3.9G of archived journals from /var/log/journal/ee4a566eacf347dbb47e03b3f33821a1.

More information on journalctl can be found here. You can find more options on removing old logs, for example limiting the total size of logs that you want to keep, using this variation which will keep only 50 MB of data:

sudo journalctl --vacuum-size=50M;

Gimp – create text for memes

In this video, we demonstrate how to create a text banner for an image that looks like the style most memes follow these days.

We are using only open source and free software for this solution so they should be accessible to everyone.