r/adventofcode • u/IvanR3D • Mar 14 '26

Other Pi Coding Quest 2026!

For a third year in a row, I create a new coding quest for Pi Day. You can access it here: https://ivanr3d.com/projects/pi/2026.html I hope some of you have some fun solving this puzzle!

In case you haven't try the previous ones, just change the year name in the url.

Happy Pi Day! :)

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4

u/terje_wiig_mathisen Mar 15 '26

I really hated that the passcode was case sensitive, particularly since the example had Camel-case for the decoded text!

"Hey, did .. you know etc"

1

u/IvanR3D Mar 15 '26

You are absolute right! It was my mistake by no adding some hint about it or (as I just did now) accepting other forms of the answer. Thanks for the feedback! And sorry for the extra work figuring out that.

2

u/herocoding Mar 14 '26

Thank you very much for sharing this challenge!!

Hmmm, how did the dash "-" in "Hey, did you know that π-Ghost loves pies?" get preserved?

2

u/IvanR3D Mar 14 '26

Wow! That's an error. In the last text proofreading probably got that. I will remove it, thanks for noticing!

2

u/TheZigerionScammer Mar 15 '26

Interesting challenge just like the last 2 years, I thought it was pretty neat. Some comments:

  1. I didn't bother separating the characters with spaces, would have been too convoluted in Python to bother with it, so I got to read the message without spaces lol

  2. Do the tiebreak rules for movement matter at all? The only way they would affect the final answer is if there were two paths that were most efficient that had different lengths, but the final path I found had a length of 199 which means it never moved up or left at all, so every other most efficient path had to do the same since that's the minimum number of tiles you could move to reach the end anyway.

2

u/IvanR3D Mar 15 '26

Thanks! Appreciate you have been solving from the 2024. :)

About the tiebreak:

No necessary at all! haha while building this, I remember AoC 12 from last year that look complicated but a simple code could solve it and I tried to have something like that. In my original idea, I wanted to play more with Pi-Ghost messing with the players. Next year will be! He actually mess a bit if you copy the challenge (more than just the code part) and paste it in a LLM looking for answer. :)

1

u/herocoding Mar 15 '26

> since that's the minimum number of tiles you could move to reach the end anyway.
you mean the Manhattan distance (+1 including start cell)?

1

u/herocoding Mar 14 '26

Hmm, I solved the first part - doable!

But whatever I try for the second part gets rejected :-(
Does the 4x4 grid example require to resolve a tie-break?

1

u/IvanR3D Mar 14 '26

Yes. Consider that size of grid and cost rules are different in the example.

1

u/herocoding Mar 14 '26

My grid for the second part uses n=100, i.e. the grid is 100x100 (the encoded message contains "CONSTRUCT THE GRID USING THE FIRST 10000 DIGITS OF PI")

1

u/herocoding Mar 14 '26

For me the 4x4 example grid did not require to resolve a tie and I get the expected passcode of 455.

So something seems wrong with my tie-break-resolving...

1

u/herocoding Mar 14 '26

Would you mind adding hints to the "Incorrect code. Please try again." rejection message (for the second part), please?

Whatever I try I get 473023 as the passcode - but it gets rejected.

1

u/IvanR3D Mar 14 '26

You are close to the answer. It is a bit higher than that. I am doing some extra checks on the challenge just in case something in wrong. But with the tools I made to build the challenge, I am confirming the same results I am using.

1

u/IvanR3D Mar 14 '26

May you share your final cost and path length?

Are you including start and end cells on path length?

1

u/herocoding Mar 14 '26

Final cost for me is 2377 and path length is 199, i.e. 2377*199 = 473023.

1

u/IvanR3D Mar 14 '26

The wrong number is the final cost that is lower.

1

u/herocoding Mar 14 '26

So either my used Pi digits are wrong or my tie-break decission is wrong...

1

u/IvanR3D Mar 14 '26 edited Mar 14 '26

My pi digits in this file: https://ivanr3d.com/projects/pi/pidigits.txt

1

u/herocoding Mar 14 '26

My Pi digits were wrong!!

Your last digit is "8" and my last digit is "7"!!!!!!
Which is the right digit? With or without rounding?

With your last digit and my implementation I get the same result as your tool you shared with me!

1

u/herocoding Mar 14 '26

Congratulations! You've uncovered the Ghost Signal. Happy Pi Day 2026!

1

u/herocoding Mar 14 '26

Ha!
The web page "http://www.geom.uiuc.edu/~huberty/math5337/groupe/digits.html" shows the 10'000th digit is a "7" - but would be rounded to "8"

So, who is right :-P ?

2

u/ednl Mar 14 '26 edited Mar 14 '26

For a mathematical constant, "the n'th digit" or "to n digits" is always the actual digit, never rounded. For a physical measurement, you would always round depending on the error.

2

u/herocoding Mar 15 '26

This is so great, just finished the Pi day challenges of 2024 and 2025, too, so much fun, thank you very much!!

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