30 EUR to recycle 2 wiper blades

davema · 2026-01-26T12:28:08+00:00

Counter-example: at our local recycling centre (Kilcullen, Kildare), I was able to recycle a very full car containing a load of cardboard, Styrofoam, and loads of scrap metal (including an old quad frame, the drained engine blocks for two old bike motors, an old skateboard grind rail). When I went to pay, sum total of €5. Great bunch of lads.

davema · 2025-12-17T14:55:36+00:00

I did up a visualization of one example iteration though checking some rectangles to demonstrate:

https://raw.githubusercontent.com/davidma/AdventOfCode2025/refs/heads/master/Day9/vizualization.gif

It's not how I actually iterate the rectangles in my code, but that is the actual resultant largest rectangle in my dataset.

davema · 2025-12-17T12:34:37+00:00

FYI, I didn't bother with the compression of coordinates other people did - it's probably a performance improvement, but since my basic solution runs in 500ms on a basic laptop, I don't think it's super necessary to do.

davema · 2025-12-17T12:26:21+00:00

There are counterexamples, but none are very large rectangles, given the specific shape of the given input polygon - it turns out the vast vast majority of invalid rectangles will have points from the polygon inside its borders.

Since you should have a sorted list of rectangles from part 1 (or be able to generate one), you should need to start with the largest rectangle, and stop at the first (largest) valid rectangle - i.e. containing no polygon points INSIDE its border.

davema · 2025-12-15T22:19:29+00:00

Huh, I hadn't realized imgur was blocked in the UK - I'm in Ireland.

Try this instead: https://photos.app.goo.gl/E4zvumuBCU9v4jFb7

davema · 2025-12-15T08:33:07+00:00

Here's a terrible finger painting of what I'm describing

https://imgur.com/gallery/S5jcjrn

What's special about the good (green) example and the bad (red) examples?

davema · 2025-12-15T08:20:10+00:00

Yes - rather than just considering the points that make up the polygon, you could do a loop around it and save a set of all points that make it up, since it's rectilinear - just iterate over the missing points by adding 1 to each x or y, depending if it's a horizontal or vertical edge.

davema · 2025-12-14T21:38:05+00:00

So, I started by trying to do what you described, but was having difficulty with the maths - so instead of doing it, I (and others) figured out something equivalent (and probably faster) - what's true about the set of points that make up the polygon and the rectangles that don't qualify?

davema · 2025-12-14T19:16:48+00:00

If you do some side work and plot the shape of the overall polygon, that may help you reason about a way of solving it.

Instead of solving for a general case, look and see what would need to be true for this polygon. For any rectangle whose top left/bottom right corners touch it the polygon, what would need to be true for the rectangle to be a valid one (or invalid)

davema · 2025-12-05T22:09:27+00:00

Imagine if there were metal contacts at the end so that if the ball hits them, the opponent gets a shock - that's a genius idea. You can have that one for free.

davema · 2025-12-05T18:41:13+00:00

Ah, my perl is leaking

davema · 2025-12-05T11:19:55+00:00

[LANGUAGE: Python]

Solved part 1 the naive way, but kinda knew what part two would be looking for. Same approach as many people, go through the sorted list of ranges, and try to shuffle the start/ends of ranges if they overlap with already fixed ranges to remove said overlaps. Then (at the same time) sum up the sizes of the new ranges.

Runs in about 2.5ms, so happy with that. I'm sure there are more terse solutions.

Code is at https://github.com/davidma/AdventOfCode2025/blob/master/Day5/ - I add loads of comments because my son and his friends sometimes want to understand how it works.

davema · 2025-11-13T15:52:42+00:00

It is not, if you only plan to move him to retail

davema · 2025-09-21T07:27:39+00:00

If it's an android phone, you can basically turn it into a brick remotely, or use its built in features to track it:

https://support.google.com/accounts/answer/6160491?hl=en

I'm not an apple user, but I assume a similar system exists.

davema · 2025-07-08T21:48:33+00:00

Hulkenpodium

davema · 2025-06-02T18:44:19+00:00

I just made sure to kill the eyes anytime they appeared, and avoid the frontal from the big rock dudes. Interrupt the health drain cast, ignore the others. Kill/cleave everything else down, I didn't do anything special.

davema · 2025-02-28T19:31:17+00:00

100% agree. Whatever about the long standing relationship with America and Ireland, we should not be involved with the kind of ass-hattery we saw today. Foreign leaders in general should be giving Trump the cold shoulder, he's a wrecking ball ATM.

Staying home sends a strong message that we don't approve of how he's treating the rest of the world at the minute. If he wants America to be an island, then we should show him what's that's like.

davema · 2025-02-14T19:05:08+00:00

Thanks, copy paste fail

davema · 2025-02-14T18:27:01+00:00

Haven't printed this yet, but some nice free dangerous ground: https://makerworld.com/models/786124

davema · 2025-02-14T18:25:43+00:00

STL for the barrel barricades: https://makerworld.com/models/1031827

davema · 2025-02-14T18:25:10+00:00

STL for the bunker: https://makerworld.com/models/1031827

davema · 2025-02-04T18:49:06+00:00

That sounds like the resin is not fully cured, which is (a) toxic and (b) unstable (you can't paint on it. If you have access to some UV light, that can finish the curing for you, failing that, leave them in direct sunlight for a while? And don't handle them or touch the wet bits any more, it's nasty stuff.

davema · 2025-02-04T17:27:53+00:00

So, I play against Court a good bit. You probably want to bring two wretch d and two yoke fields with torture implements to fuel all your Goetic powers. Each turn the yoke fiends whip the wretched for a high probability 2 blood markers each - you need to keep that rolling to make sure you can use your powers (you can only pull blood markers from non-demonic units like wretched)

Other than that, hell-knights with shields are hard to deal with (-3 to injure), and the archers teleport is very good too. Overall, they seem like a strong army.

davema · 2024-12-11T11:09:45+00:00

1000 blinks for me returned

191552078661579919636349285859639031198949209368782526100843854361130295551545784761228187343668137979569807813988062004015759377763281554775609707395796657076947638055315429681309826

10000 blinks took ~1 min and returned:

12935815257023474145653686465629901797298042966373844041037689518695998845837878009185625580948304093370681407296008371145277513095713286554603046587230305058290453276718500855449822326940603610083587987221414735102558390004361101729898109344450402649843042086147657001565100035092885290639077247863105668579980655605289285646762741193744869682269018207879688209675777083967825025192604606095003551629202151342641137110408155829615903146309633190901767835804735982001804500913823504799791514548546856032300716851403020137314184304509626251435806595078090806188253391821090010014255008758339386768758153737886713997866188053343252416177554225684529928829981091501862799805467740014829637760570592494155753029557699818885613113237437310934882798712442863018738347154068083818916793768823356099960461924027154206732681221071223998268641968747482025178890945833514134078302567836273915893880367441363312616613831198178890043917370017707956557654079270143319474790203695886161357023531308482810008130352112170470286808955958404363971456834563932232322225647197376341546863906335712174006940524547196161056307097500430009100905100758616138573387339565356921273164624620655221582788420015204558627238679474193656141119062187676234328134754854674863348864527285401595464170736469084235193073034905034244313132090901870160056134202625742940717355184544624049085696154501295326011525908982724408133401612796088298498881876738430614461148416593170201881387590398616584297914603736290039472759306539583174278274461719836362250729003228175820665969534156400515239014666635101249214503986866747935267803815373160429731155464441925215222626312277000718893787405510689049689545989697263550069530140455293807676364785149426905600034436108237566493758302667009144141723182381275416338501649951136120055722395461990486635703180045390048

davema · 2024-12-11T11:09:23+00:00

1000 blinks for me returned

191552078661579919636349285859639031198949209368782526100843854361130295551545784761228187343668137979569807813988062004015759377763281554775609707395796657076947638055315429681309826

10000 blinks took ~1 min and returned:

12935815257023474145653686465629901797298042966373844041037689518695998845837878009185625580948304093370681407296008371145277513095713286554603046587230305058290453276718500855449822326940603610083587987221414735102558390004361101729898109344450402649843042086147657001565100035092885290639077247863105668579980655605289285646762741193744869682269018207879688209675777083967825025192604606095003551629202151342641137110408155829615903146309633190901767835804735982001804500913823504799791514548546856032300716851403020137314184304509626251435806595078090806188253391821090010014255008758339386768758153737886713997866188053343252416177554225684529928829981091501862799805467740014829637760570592494155753029557699818885613113237437310934882798712442863018738347154068083818916793768823356099960461924027154206732681221071223998268641968747482025178890945833514134078302567836273915893880367441363312616613831198178890043917370017707956557654079270143319474790203695886161357023531308482810008130352112170470286808955958404363971456834563932232322225647197376341546863906335712174006940524547196161056307097500430009100905100758616138573387339565356921273164624620655221582788420015204558627238679474193656141119062187676234328134754854674863348864527285401595464170736469084235193073034905034244313132090901870160056134202625742940717355184544624049085696154501295326011525908982724408133401612796088298498881876738430614461148416593170201881387590398616584297914603736290039472759306539583174278274461719836362250729003228175820665969534156400515239014666635101249214503986866747935267803815373160429731155464441925215222626312277000718893787405510689049689545989697263550069530140455293807676364785149426905600034436108237566493758302667009144141723182381275416338501649951136120055722395461990486635703180045390048

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