This is a recurring post to discuss programming or other technical projects that we've been working on. Tell us about one of your recent projects, either at work or personal projects. What's interesting about it? Are you having trouble with anything?

Today's problem description: https://adventofcode.com/2025/day/6

Please post your solutions in your own top-level comment. Here's a template you can copy-paste into your comment to format it nicely, with the code collapsed by default inside an expandable section with syntax highlighting (you can replace python with any of the "short names" listed in this page of supported languages):

<details>
<summary>Part 1</summary>

```python
Your code here.
```

</details>

Today's problem description: https://adventofcode.com/2025/day/7

Please post your solutions in your own top-level comment. Here's a template you can copy-paste into your comment to format it nicely, with the code collapsed by default inside an expandable section with syntax highlighting (you can replace python with any of the "short names" listed in this page of supported languages):

<details>
<summary>Part 1</summary>

```python
Your code here.
```

</details>

I recently set up some public computers with Ubuntu at a hackerspace. People kept logging into their Gmail etc. and forgetting to log out. For their own benefit I changed the computers to use overlayfs so on reboot all changes from the base filesystem (Ubuntu 24.04 + packages + updates) are lost. I'm looking for tips on configuration. Keep in mind that because our users tend to be fairly technical I am not attempting to outright prevent changes, just prevent them by default.

Here are the current details:

• The machines have a wallpaper warning users that all changes are wiped on reboot
• The normal automatic update system is disabled (updates through it won't persist)
• I install updates and reboot on a cronjob at 5am every day (this uses overlayroot-chroot)
• The overlay is implemented as an encrypted filesystem on a separate partition, with the key generated on boot and held in memory
• Documentation is taped to the desktop computer itself educating users on how to make persistent changes

Today's problem description: https://adventofcode.com/2025/day/12

Please post your solutions in your own top-level comment. Here's a template you can copy-paste into your comment to format it nicely, with the code collapsed by default inside an expandable section with syntax highlighting (you can replace python with any of the "short names" listed in this page of supported languages):

<details>
<summary>Part 1</summary>

```python
Your code here.
```

</details>

Today's problem description: https://adventofcode.com/2025/day/10

Please post your solutions in your own top-level comment. Here's a template you can copy-paste into your comment to format it nicely, with the code collapsed by default inside an expandable section with syntax highlighting (you can replace python with any of the "short names" listed in this page of supported languages):

<details>
<summary>Part 1</summary>

```python
Your code here.
```

</details>

Today's problem description: https://adventofcode.com/2025/day/11

Please post your solutions in your own top-level comment. Here's a template you can copy-paste into your comment to format it nicely, with the code collapsed by default inside an expandable section with syntax highlighting (you can replace python with any of the "short names" listed in this page of supported languages):

<details>
<summary>Part 1</summary>

```python
Your code here.
```

</details>

Today's problem description: https://adventofcode.com/2025/day/9

Please post your solutions in your own top-level comment. Here's a template you can copy-paste into your comment to format it nicely, with the code collapsed by default inside an expandable section with syntax highlighting (you can replace python with any of the "short names" listed in this page of supported languages):

<details>
<summary>Part 1</summary>

```python
Your code here.
```

</details>

This is a recurring post to discuss programming or other technical projects that we've been working on. Tell us about one of your recent projects, either at work or personal projects. What's interesting about it? Are you having trouble with anything?

Today's problem description: https://adventofcode.com/2025/day/8

Please post your solutions in your own top-level comment. Here's a template you can copy-paste into your comment to format it nicely, with the code collapsed by default inside an expandable section with syntax highlighting (you can replace python with any of the "short names" listed in this page of supported languages):

<details>
<summary>Part 1</summary>

```python
Your code here.
```

</details>

Today's problem description: https://adventofcode.com/2025/day/5

Please post your solutions in your own top-level comment. Here's a template you can copy-paste into your comment to format it nicely, with the code collapsed by default inside an expandable section with syntax highlighting (you can replace python with any of the "short names" listed in this page of supported languages):

<details>
<summary>Part 1</summary>

```python
Your code here.
```

</details>

Today's problem description: https://adventofcode.com/2025/day/4

Please post your solutions in your own top-level comment. Here's a template you can copy-paste into your comment to format it nicely, with the code collapsed by default inside an expandable section with syntax highlighting (you can replace python with any of the "short names" listed in this page of supported languages):

<details>
<summary>Part 1</summary>

```python
Your code here.
```

</details>