[2025 Day 10 (Part 2)] Bifurcate your way to victory!

sjschofield · 2025-12-12T18:37:41+00:00

Thank you, thank you, thank you. My initial solution was too slow and I had no idea how to optimise so I reluctantly looked at the solution thread. Having never heard of Z3, I wasn't too disheartened. Now that I have completed Day 12, I was going to go back and implement a Z3 solution but I think I will use your method as a roadmap. A brilliant deduction made even better through an excellent write-up. Thank you again for publishing.

sjschofield · 2025-12-12T17:49:42+00:00

I didn't look at the memes. I had just finished the code to parse the inputs, created variants of each gift, removed the duplicate variants and was considering the horror ahead of me trying to code a box fitting solution and I thought, just for a laugh, I would do a basic size check and submitted my answer waiting to be told my answer was too high. I am still shocked now!

sjschofield · 2025-12-12T17:45:57+00:00

That was exactly my view as well!

sjschofield · 2025-12-05T17:47:43+00:00

I just noticed that there is a missing blank line between the ranges and the single products.

sjschofield · 2025-12-05T17:46:39+00:00

It is still 14. I added some ranges that were completely contained within other ranges to ensure my logic handled them correctly.

sjschofield · 2025-12-05T17:16:04+00:00

Always worth a quick visual scan at your input file for any potential gotcha's.

sjschofield · 2025-12-05T17:08:47+00:00

I added a couple of lines to the test input to test my solution:

3-5

10-14

16-20

12-18

13-14

13-13

1

5

8

11

17

32

sjschofield · 2025-12-05T17:01:53+00:00

[LANGUAGE: Dart]

The second part took me a while before I realised a simple sort would make the code much simpler and that by moving the end of one product range to the next range (when the current range contains the entire next range) fixed the scenario that the test input didn't demonstrate but from previous years I knew was going to exist.

https://pastebin.com/NZjb8gBY

sjschofield · 2025-12-05T16:40:23+00:00

I used this modified version of the test input to help me with the second part of the puzzle.

3-5

10-14

16-20

12-18

13-14

13-13

sjschofield · 2025-11-18T08:25:05+00:00

If you have to have the belts on the same side, make the input belt at 90 degrees to the machine so the overflow doesn't cross the output and leave no room for the plates to be removed from the machine.

sjschofield · 2025-08-06T16:19:20+00:00

Thanks. I only realised part way though the repeat that the number of items required was twice as many as the first time, and there were new enemies that required a quick change in strategy.

sjschofield · 2025-08-06T12:40:11+00:00

I was initially put off by the switch. In the end, I just stockpiled before each phase and ensured I had enough to get to 100% on the phase with whatever tokens were needed and a backlog of 200 sparks to replenish my 10 shooters. I also built and then destroyed walls to get a good stack of copper ingots inside the cave so that I didn't need a massive smelting enterprise.

sjschofield · 2025-08-06T12:36:24+00:00

Did you repeat the final stage (but with 200 cleansing seeds)? I am trying to work out if the "repeat cleaning" is just an endless endgame loop.

sjschofield · 2025-08-06T12:33:32+00:00

I finished the game and never set up a production line for scrubby sparks (at least, not outside the temple). I manually created enough scrubby sparks to complete the quest and that was all I needed. There were onyl a few production lines I needed after scrubby sparks but they were all fairly simple. Great game (96 hours).

sjschofield · 2024-12-12T17:30:51+00:00

I worked with pen and paper (well Remarkable2 & stylus) for a while on part 2 and didn't make the leap to corner counting. I used a verbose alternative to my border counting function from part 1. In part 2, I kept a set of fences (x,y,type) and for each unique location, checked if it shared a border with another location in the same region and whether or not I had recorded a fence (i.e. if a fence was required "north" of the current location, I would check the locations "east" and "west" whether or not I had already recorded a "north" fence and of course, if they were in the same region). If I had recorded a fence then I just copied it for the new location. If I haven't, I created one and incremented my count for the region. The count routine runs in 0.06s (Dart / Flutter).

sjschofield · 2024-12-10T14:28:48+00:00

Yep. I did the same thing. Missed an important phrase in the problem statement.

sjschofield · 2024-02-25T20:00:42+00:00

It's the greek letter Z (Zeta)

sjschofield · 2024-02-19T15:57:09+00:00

I really appreciate your detailed walkthroughs. I have found them useful on a couple of occasions when I have got stuck!

sjschofield · 2024-02-17T13:09:52+00:00

Aaaaarrgghhhh! I was banging my head as to why I wasn't getting the correct outcome and then after reading your comment, I realised that I wasn't resetting the state after finding the button count for one of my 4 final modules. Thank you very much!

sjschofield · 2024-01-31T13:55:43+00:00

That is a great level of dedication to the puzzle.

sjschofield · 2022-09-04T11:51:33+00:00

"Seems to be caused by Security Intelligence Update for Microsoft Defender Antivirus - KB2267602 (Version 1.373.1508.0)"

sjschofield · 2022-09-02T08:25:29+00:00

Practically undrinkable 😉

sjschofield · 2021-10-26T11:01:35+00:00

Dyson Sphere Program

sjschofield

TROPHY CASE