Advent of Code in Haskell 2023 - Day 16 and Day 17 sneakpeek

all right welcome to the stream we're doing day 16 of the Advent of code um I took a break yesterday to go to a wedding but we're back let's see if we manage to catch up and uh solve it quickly maybe we'll manage to catch up today I don't know I'm waiting for maybe 2 hours not too long but let's see let's get on with day 16 all right the floor will be Lava so we use the lens Library I like that shout out uh light is complete focus on where lava production facility the Cave the okay finally the hard the mountain you see bright light Inc ahe okay we focus the light on something camera close the facility pulling okay the contraction seem to be a flat two dimensional Square grid nice empty space mirrors and Glitters okay the contration most of the beams around the grid but each tile in the grid converts some of the beams L into heat to move the rock in the cavern so we have the layout comes in in the upper left top left corner from the left and heading to the right then its behavior depends on what it encounters as it moves if the beam encounters empty space it continues in the same direction theam encounters a just check mirror ah the beam is reflected right so it goes like Ching it goes through here and here so if it goes here it would start going downwards okay if the beam encounters the pointy end of a splinter the beam passes through SP okay but flat side of the splitter as here the BL split into two beams going in each of the two directions and the Splitters Point these ends are pointing aha okay one that goes up and one that goes down cool okay let's parse this quickly into something that makes sense I think we're going to use a an array cuz we're going to be navigating around and we want that that random access bro it's the best kind of access well you have to [Music] uh keep it all in memory though but that's okay that's what we're going to do anyway example okay also my mouse is working again it's not working for a while but now it's working again let's all celebrate that it's also third Advent this Sunday um because Christmas Day is on a Monday so like next so the Christmas Eve is actually fourth Advent that is crazy yo anyway in Iceland uh we lit light four candles but we haven't been home these uh advents so we haven't really been doing that uh but that's okay we're doing ad of code instead wow feel like my uh laptop is slow today like the rendering is just a bit slow but it's okay we're still we're still on a server so Solutions time shouldn't be affected but I'm going to go ahead and um save everything here now how do we do uh an array let me see so um the things in this uh grade are going to be data G create entry so we're going to have a empty space we are going to have reflect 90 okay so let's have another data type that just says data angle how is the audio by the way is everything good I feel like like my laptop is not in a good mood today I hope it's going okay OBS is reporting things okay but yeah you never know let's see up down left right okay [Music] um um I'm actually going to just make it at an array of characters right [Music] um reflect 90 and then it's either uh it's going from from left to [Music] up left comma up uh it's reflect H and then it's angle angle so we're going to have the left corner and upper right right corner okay then we're going to have a splitter and that's all so angle angle um left right left right or uh right or damn I feel like um I feel like it's actually like a you can imagine these slashes uh uh also as as a splitter but it's just um just it it's changing the direction um but it's not creating to anyway um so let's see hle dat. array I never remember how these things work uh we're not doing B arrays um maybe it's in container I think it should be in containers it's like Ira and mras and uh has scale container [Music] package what what is going on today Jesus we go so map. strict data. map any containers yes okay good containers don't have uh arrays data do array yeah it's an ARR array package makes [Music] sense let me see um I want to just say here uh um let's just import data. array I'm just going to make it figure out the types itself uh do print so um read file example into print. pars so pars is equal to Lin a pars is equal to uh map pars [Music] entry pars this of strings into and this is just going to be a list of list of grade entry no uh let's see pars where uh par entry dot is equal to empty first entry uh Slash is equal to reflect a from a left to right so it's either left to right or right to left right [Music] how do they describe it in the text so right from the continue upward let's actually make this just an angle okay uh so this one if I'm coming from the right I'm going to go up fars entry I think these are all the same okay I think it's it's actually you know it's like this so so uh data grid entry is just a GE of list of angle okay so this is GE Mt this is GE [Music] up and uh if you come from the left okay okay this is G down maybe these type selections are going to bite Us in the end that's it we need to do it like this CU otherwise it's going to be messed up par entry so I think it's a nice choice of entries here that would actually let this up down let's kind of say if you go through this these are the copies you're supposed to um create okay let's see D see o day 16 day 16 T CH and time 16 it's a member oh my God install liay what it's a bit annoying with the GT up is it doesn't come with all the batteries included so now I feel like see and then we just installed it it it was already there which just kind of not exposed uh globally okay map [Music] map dering show we should probably add you know EQ or whatever here okay so we have empty list up down dot dot okay now I want to make this into an array and there's going to be a mutable arrays uh um let me see B of the array spe lowest and highest bound ofray extrac and a one origin okay okay then we're going to just say um let's make this into int common and then these are going to be int comma okay and this is going to be a map so we're going to sip and then we're going to [Music] zip map is applied to yeah okay I need to do dot here [Music] okay [Music] um the zip WID okay and then instead of doing like this I'm going to say here I uh ILS to um we're going to map A J comma e to I comma J comma [Music] e let okay and right and then it's like [Music] this let's see again okay now we have the all the [Music] associations and now let's just concave [Music] why can't [Music] I conat all of these [Music] um print parts and then [Music] conet I feel like I should be able to do conad here ah it's because I didn't change the type here okay nice okay and now I am going to make this into an my array um what is this U array it's that uh un it's unboxed okay array and let's see array int int grd entry and then we are going to say here import or qualify data array as R import data array [Music] array and then what I'm going to say here is I'm going to say r dot from list a list array here um ah array and we just say that the bounds should be 0 0 and 9A 9 right yes do nice okay and and then I can kind of move around in the array right so now let's [Music] see do so a r is it just this and now let's see return here print our and I should be do print are uh 1.2 yeah okay so now I have fast access to to the values in the array cool this is all quite nice and fast so now we have the layout in here here so now I'm going to [Music] um let's see now I need to write the opposite [Music] function opposite Up Is Down opposite down is up opposite left is right and the opposite of right is left so we will let's just always start um we start at 0 0 and what we're going to do is that every time we are supposed to split the beam we're just going to save that in a list of beams that we have to process next okay so we are going to say here um part one and then we can probably memorize it later it's going to be go so this going to be um empty so we're going to start with the beam 0 comma 0 that's going right okay and that's going to be our initial one so where go and what I want to see [Music] is if I so what uh what tiles have I seen okay so we do um we have to have a set for this import data do set set import qualify data do set as set so we're going to have here um set. empty so go uh so if I don't have any beams anymore I'm just going to here in set. size scene now okay go [Music] scene uh beam coordinates and beam Direction and these are the other beams [Music] uh m [Music] okay so here oh okay so what I know is actually that [Music] um let's make this a map. empty actually map. empty um and we're going to make this import data. map map import qualified data. map as so we're going to make this a map. empt and map. scene okay so here we're going to say a gohing case um so just H visit it so seen uh just uh at BC uh uh scene map. bang question mark um let me see if I've never seen it before case um scene map. bang um and BC of so just there's okay so now I'm going to see if um if I've seen it before and it was going in the same direction it's not going to change anything cuz it's just going to hit everything again uh so uh if BD uh set. member let see set dot what is the type of set. member again I never remember it I never remember the which comes first the map or the okay the element cons froms uh if a PD set out member uh de then go other beams otherwise then go see other beams else um okay [Music] so it's basically this okay it so let's just do it here just of seen scen map. BC uh so we we have seen this style before first of all and H BD set that remember there's is equal to go seeing other themes otherwise [Music] um okay otherwise um okay otherwise we haven't seen [Music] it before then we have to create [Music] um okay otherwise so then we say uh let scene Prime equal um map. Singleton a oh does map not single T [Music] work okay it says key value okay map. single turn um BC and then set. Singleton BD in [Music] um in a scene okay so we say map do insert ah okay I don't need to do that so map. insert with uh this and then BC and um set. single volon PD and this is a set. union let same Prime is equal to to this so this is a new set so we're just going to add this new Direction let C Prime equals map. insert with set. Union and then the coordinate and then this new and then scene so that's the in uh go scene Prime beams Prime um now we need to say beams Prime okay so beams so um now we have to add new beams so let's say we actually figured out the new scene Prime so let's say uh case um and then now we're going to look look up in this array right R we're going to say case r r do bang VC [Music] of okay um let's see here move uh X comma y uh so we're moving to the left is equal to uh but I yeah I zipped it so it's actually y comma X as usual X as usual so this is going to be y comma x -1 if I go right it's going to be x + 1 if I go up it's going to be x minus one actually and if I go down it's going to be y + one okay case RBD of G empty so if we hit the empty list then um the new beam then we're just going to say um uh let's see new beam is equal to okay okay if we um hit the empty list then this is going to be um the same as move [Music] um BC BD let me see data. array we look up and [Music] um what happens if it's out of bounds probably get an error right okay and okay so the new beam is just uh we just do it we just have one element okay if I hit the uh one with a one case then um let me see I think [Music] they let's see okay if I hit uh an up uh that is a k b a BD of so if I hitting one that goes up which is [Music] a this one right yes so if I'm coming from the a right so if I'm going right if if this is so case speed of right the new direction is uh up so we are just going to say move BC uh move BC BD and then the next one and is also BD okay move BC a up up okay if I'm coming from the left it's move BC um down down if I'm coming from the if I'm coming up then it's move VC uh then we're going we go right and down then we go left [Music] and the other case here is down so if I'm coming down okay and if I'm coming from the right I want to go down if I'm coming to the left I want to go up if I'm coming if I'm going up I want to go left and if I'm going down I want to go [Music] right okay now they are two more cases the [Music] Splitters uh oh this one is up down this one's supposed to be left right [Music] okay so if I'm coming from the uh from coming from the right or left if I come to the right or left the um [Music] the is left or the is right then I want to go um one that goes up [Music] and um otherwise it is just move bcbd same here with left and right left right um if I was going up so this one uh this one was going up or down then I want to go this is be down and going be left and left and right and right otherwise I just continue going and this is the new beam [Music] in let me make this a bit smaller [Music] maybe okay in go S Prime and we want to do new beam other [Music] mes okay [Music] um last do be depending where it moves okay I guess if it um if it um if it escapes the bounds then um if it escapes the bounds then we [Music] just [Music] so let's just first make sure we remove anything that's not within pounds okay um BC bcpd and I don't care about this and I I want to say um case so let's see these are and then let's see [Music] um b y okay let's just make sure that um so uh bound so R not bounds let me see um XY so let's see um X is larger equal z and y is less larger than equal Z let's get a a BX comma py out of um array bounds f r and then let's check that X is larger than zero and Y is larger than zero and X is less than or equal to BX and Y is less than or equal to b y right um and then this is just RS so if this is if not this then go then just keep going go s RS let's see probably going [Music] to Let's import preload hiding left right these are from either [Music] so language GC 2021 M um num angle [Music] move and in Comm [Music] in angle to in my [Music] in let me see and the go is supposed to be um go is a takes a map of um int comma int and set angle I call it Angle now yeah uh to a uh [Music] um a list of in comma in comma angle these are the beams and we'll return an [Music] INT and it's because I looked up the wrong thing here okay or B see [Music] okay part one array in comma int um gr and TR to um in okay so the bi I uh because it gives the lower bounds and the upper bounds I get it okay um LBX lb y ubx UB y LX y ubx [Music] UI okay um it does do something now let's see print part one R okay give us 46 for the example and it does so quite fast [Music] um let's see um part [Music] one great entry H and I just need to print it does seem to work for the example now let's just see if it works for the input um before we start debugging I think it should [Music] work basically we kind of memorize it at the same time as we write it with this um error in Array [Music] index [Music] okay [Music] let me see um Trace show [Music] um Prett show um let's just do try show actually uh BC [Music] um indentations go bur yeah a import debug. [Music] Trace [Music] H [Music] what is it just not even uh print. part one [Music] okay it works for the [Music] example I thought I specifically checked the [Music] let me um first pause it and say R2 um print bounds R2 okay return return error in Array index is it just failing on the pars then ah okay that's funny Ah that's okay that's the problem uh it should start with 0 comma 0 and it should end [Music] with R [Music] equals h f red equals f f STS um okay so to start with z0 and we should end with the first of the last of r where this is St okay now we have the actual index here and print part [Music] one 8539 okay seems like a reasonable number all right we did part one whoop took us 40 minutes though but we did a lot of work uh the reinder talks in your Shir collection any Edge tile and heading away from that edge for the beam starts in the bottom right corner start heading either left or upward so the beam could start on any tile any tile in left the bottom row any tile in left most column or any tile in the rightmost column to produce lava you need to find the configuration that energizes as many tiles as possible this is going to 51 tiles are energized find ini being configuration eniz is the largest number of tiles uh okay um let's just write here uh fun takes in and in comma int and angle and returns and and then takes an array [Music] and then a list of this and returns and int okay and we're going to call this part fun our beams beams part [Music] one uh R is equal to fun R and 0 comma 0 [Music] right no this this work yes [Music] okay now um I think I'll just run it over all of them okay um so part two are it's going to take um so we're going to have a where LBX lb y ubx u y is equal to r. bounds R okay so um the edges are going to be um oh my go edges are going to be um it's going to be uh how do I do this so H we we're going to have the left Edge is going to be map I a to so 0 comma I comma right um ages is equal to uh this mapped over zero uh it's actually yeah but it's going to be this lb X and then this is we're going to have this be Y and this is y and this is from LBX no from LB y to Ubbi concatenated with um so these are the ones going right so this is the right Edge and then we have the left Edge and then we're going to have the uh little going left and that's going to be the ubx I think I need to say uh plus one actually to make it to the end and then we're going to do for the X's we're going to do X and lower b y and this is going to be going down and it's going to go from low X to u x + one and then we're going to do upper bound X go up and then it's going to be lower b x okay let's just write edges here first and see what [Music] happens and part [Music] two so we got all the right ones from zero to nine ah it goes to 10 also okay so we don't need this plus one here okay this one goes to 0 to9 and then we have a I think these are all the edges okay um maximum of um [Music] maximum of um map f [Music] r e fun r [Music] e oh let's just actually make this like this this is just fun our um probably be better if we like share [Music] the share the cashes between them um but whatever let's see if this is super slow or [Music] not when r e edges uh gives [Music] 51 that's not 51 that's [Music] 48 a being can start on any tile in a h on heading downward ah I messed it up these are actually um the coordinates are flipped right so it's actually these are supposed to be yse y y and this will be LX Y and these are going to be x and x um but I think they're both actually let me get 51 I think cuz they're all square these things here actually don't matter um let's have it correct let's have this correct okay so now this is the right end and the left Edge but this one should actually be going from a yeah they are they are correct let's just see how bad is it for the input it's going to take some while um okay 7 Seconds all right we did D16 whoop whoop didn't take us too long but all through the power of aray let's see get status get add day 16. HS input here commit M day 60 you push okay let's go to day 17 then I don't know if we're going to finish it today um but it' be good to get some progress on it uh and then maybe we'll finally call catch up right oh not finally like we're just one day behind CU we skipped one day let me see okay day 17 anyway I like the solution here it was a just erase and then we just brand the thing there was not clever this it was just about getting it correct memorizing with this so just realizing that if you're getting have a [Music] beam um going hitting the same tile going the same direction it's not going to do anything new right okay but now day 17 Oscar Allen says it wasn't too bad oo look at these CSS effects there is lava coming down this is crazy stuff okay uh let's [Music] see clumsy Crucible ly okay there's a parachute CU we get to gear Island and there's a giant Factory here okay we have a lava fall large Crucible top heavy unfortunately difficult to steer and so I can't C to go straight line for very long okay you need to find the best way to get The Crucible from the lava pool to the machine parts factory to do this you need to minimize heat loss while choosing a route that doesn't require The Crucible to go in a straight line for too long fortunately the elves here have a map that uses traffic patterns Happ damage parameters okay this is going to be some breath for search kind of yes anyway that's I think we implemented it so many times er in the past few years and it's high time we did it this year right let see module main wear main iio main equals return and um first let's par the example I feel like each City B single digit repr amount of heat loss uh the starting point pop left City Block the destination the machine parts factory is a bottom right City Block because you already start in the top left block you don't incur that Block's heat loss unless you leave that block and then return it to it okay okay can move at most three blocks in a single Direction before it must turn 90 degrees left or right so that basically says um [Music] hello yeah day 17 little Lenny we finished day 16 we're going to take a quick look I think I'm going to stop in like 40 minutes uh I need to sleep also okay one way to minimize heat loss is is this path never moves more than three consecutive blocks in the same direction incre a heat loss of only 102 okay so cuz it's it's not just breath ver search right it is also we also need to be careful that the path uh satisfies the [Music] property it may nor only turn left continue straight or turn [Music] right [Music] m okay let's um just start with um the breath for search [Music] then how do you do the breath for search again um we also we don't need [Music] to just uh remember what it was bre [Music] search three that property okay and then we do the on explored and then route and if we is a go then return [Music] we maybe I should like for every note say that you can [Music] do let me oh I'm getting some milk delivered while Q is not empty too so we need like a priority Cube and then we just need to be careful with the path that we take right because it's not valid to just say oh we take the shortest path right um [Music] um [Music] so what if I do breath first search and then um for the Neighbors that's the thing right I can't just say ah for the neighbors just if you've gone three times to the right just throw out those neighbors right because uh the the path it's path independent right [Music] um [Music] cuz I'm not like I'm also you know we're also in that case where um I just have like half an hour left and I'm like I'm going to start doing breath first search and then that's not going to work um so what I want to kind of do is just uh pause it here and let's just do day 17 tomorrow right and just give me some time to think about it I feel like I feel like I need uh to think about this a bit so let's see um path here so it's goes 34 and then 32 [Music] 31 we could also you know [Music] try just the super greedy algorithm right it always just chooses the um chooses the smallest one it can this is say kind of you know the shortest path to this point is the shortest valid path to all of these points right and then the shortest valid path to any of these points and so on right so you will kind of do it recursively uh but backwards but that's problematic by saying that um yeah maybe we can do it like backwards like backwards shortest path kind of [Music] okay let's but let's start at least by um Haring it we're going to do something similar as in day 16 we're just going to we're just going to have all these things you know we're going to talk about directions and angles and stuff let's call this uh there section and then we're going to do uh import preload hiding left left right so and we're going to we have to import all the all these [Music] dependencies okay a grid entry here and this is actually not great entries it's just numbers in um and pars entry C is going to be read at in see and we have the pars and they are directions well let's do read file example um print do bars ni GT o day 17 just 17 h no day 17 day 17 30 CH and [Music] time okay then we have this grid array sorry [Music] okay then we can have something like paths and like scene I just don't know how to like if we just supposed to find the shortest path that would be easy right but I don't know how to it's quite hard to put this extra constraint on the path [Music] that [Music] so what I want to do is I want to yeah okay but at least we have uh we have it parsed for now and uh we can move around in it right [Music] yeah I'm going to pause for now sorry about that I am just not I'm not getting like a oh this is how we can do it so I'll pause for today and H hopefully to come back tomorrow with you know something written down like I had for green serum and uh yeah we'll see how we fix it all right but thank you for tuning in today uh hope you enjoy day break and I'll see you again tomorrow for uh well day 17 uh again thank you Oscar okay byebye