Day 08

day08/default.nix

@@ -0,0 +1,113 @@
+{ pkgs, lib }:
+
+with lib;
+
+let
+  calculateTreeVisibilityForLine = line: let
+    updateState = { currentMax ? (-1), trees ? [] }: tree:
+      if tree > currentMax then { currentMax = tree; trees = trees ++ [true]; }
+                           else { inherit currentMax; trees = trees ++ [false]; };
+    forwards = (foldl updateState { } line).trees;
+    backwards = reverseList (foldr (flip updateState) { } line).trees;
+  in zipListsWith or forwards backwards;
+
+  transpose = grid: 
+    genList (n: map ((flip elemAt) n) grid) (length grid);
+
+  combineGridsWith = f: grid1: grid2: let
+    height = length grid1;
+    width = length (elemAt grid1 0);
+    elemAt' = row: col: grid: elemAt (elemAt grid row) col;
+    generator = row: col: f (elemAt' row col grid1) (elemAt' row col grid2);
+  in genList (row: genList (col: generator row col) width) height;
+
+  trees = pipe ./input.txt [
+    fileContents
+    (splitString "\n")
+    (map (splitString ""))
+    (map tail)
+    (map init)
+    (map (map toInt))
+  ];
+
+  treeVisibleGrid = pipe trees [
+    (lines: { horizontal = lines; vertical = transpose lines; })
+    (mapAttrs (_: map calculateTreeVisibilityForLine))
+    ({horizontal, vertical}: { inherit horizontal; vertical = transpose vertical; })
+    ({horizontal, vertical}: combineGridsWith or horizontal vertical)
+  ];
+
+  visualization = let
+    genColor = name: command: builtins.readFile
+      (pkgs.runCommand name {
+        buildInputs = [ pkgs.ncurses ];
+      } "tput ${command} > $out");
+    red = genColor "red" "setaf 1";
+    green = genColor "green" "setaf 2";
+    clear = genColor "clear" "sgr0";
+
+    greenRedTree = visible: tree:
+      if visible then "${green}${tree}${clear}"
+                 else "${red}${tree}${clear}";
+
+  in pipe trees [
+    (map (map toString))
+    (combineGridsWith greenRedTree treeVisibleGrid)
+    (map (concatStringsSep ""))
+    (concatStringsSep "\n")
+  ];
+
+  answer1 = pipe treeVisibleGrid [
+    (map (count id))
+    (foldr add 0)
+    toString
+  ];
+
+  countUntil = stopPred: xs:
+    if xs == [] then 0
+    else if stopPred (head xs) then 1
+    else 1 + (countUntil stopPred (tail xs));
+
+  visibleDistanceBackwards = line: let
+    measure = trees: size: let
+      newTree = {
+        inherit size;
+        viewDistance = countUntil (x: x.size >= size) trees;
+      };
+    in [newTree] ++ trees;
+  in pipe line [
+    (foldl measure [])
+    (map (x: x.viewDistance))
+    reverseList
+  ];
+
+  visibleDistanceHorizontal = line: let
+    backwards = visibleDistanceBackwards line;
+    forwards = pipe line [
+      reverseList
+      visibleDistanceBackwards 
+      reverseList
+    ];
+  in zipListsWith (x: y: x * y) forwards backwards;
+
+  answer2 = pipe trees [
+    (lines: { horizontal = lines; vertical = transpose lines; })
+    (mapAttrs (_: map visibleDistanceHorizontal))
+    ({horizontal, vertical}: { inherit horizontal; vertical = transpose vertical; })
+    ({horizontal, vertical}: combineGridsWith (x: y: x * y) horizontal vertical)
+    (map (foldr max 0))
+    (foldr max 0)
+    toString
+  ];
+
+in pkgs.writeText "answers" ''
+  Task1:
+    ${answer1}
+
+  Visualization:
+
+  ${visualization}
+
+  Task2:
+    ${answer2}
+''

day08/input.txt

@@ -0,0 +1,99 @@
+020111211022103023211142403044034010412103202221251542233334311102303044440313120021223120332211221
+121001110111201102213124201444431204213221413222211111444444412110041144131210002230130121313101010
+112010221202200121420032021412024323255214355122345552225213252324112400440302313420323102103100221
+211022232121222123201224234031435144114512425232345144523531533222344004011342234110131312300332202
+202103101023303021233104321411251553151424242531344221312225231225524421412434024103021300123300121
+202122200002211022342141123051132352344252152315525324551424132421225143201002114204223302333232221
+011310312223223421431113235421121321152124551441143435255214322514544552225412313011414423301132102
+121331322013001133311000223433443341113554412556562564315233144532455221433431002003332002203013201
+003201332004241133340023541532333131413153266664363423353232622124454254554345422200200433100333102
+230030131344203011040552414515334144165664524445366334422626244444323115333252423443232113432003211
+020300112334333142144323414353551436334563654426436625356343222253643212532215422020214344013310331
+220002231221003314452445344223355655546325233543653632544634656464243551334233433413423044300230210
+111022100242320043435324555421362243363346366346456252353246655455262455415331454531201000441410231
+101232013434204241242451442362524554225656254252456532663634445256345634451144555513214431300213021
+021113211441142541244515256653533353262654644343347336234522332254544443346322422154143020040021110
+002032342223245141521455555365463263562446777664546776637635443223664266645633333231151132112140113
+002033421301452414544444345232465536465366346553375665564756366435442422632435555111445311104203133
+332303032232445231354236322622423634433537753546335477544636344436526324435436522445155410213401230
+214021124335354212514535634245552337436663757533364556376776733565333462254562365531354214423412431
+231123230423124441525624265443647673566756453545563655373357453547537663433453433212213223101140424
+100211320333154123522263362425466444634667564437776546465446345667366445453365366551352122420231230
+024400401554531424535342424657437377754456437376767656436366374765557746355562226364213315421212320
+214442223135544515264335435467756354735433346664764464468465443746334373746425422542525455354340110
+141333001441254326655252563743544735555378755475567457777687677357576573543344653346551442221242312
+022033123224325536562464253467675635635678458757477754757874576653435356676234462564555551451230022
+444402313413432333426636637636453646648557685556587678886878777785454364533433543362622525453201222
+031024134513414333456224636475357556855564445765756678575486648885765563445546566235352311454320030
+341331341415512452344636337436467675565575756658588888477584775646657736366434365523664142235144413
+333344214132152543325563654447567486457556845676545687457688885466457333476777342344625323533242333
+203124152315365546566375565336778768544768846599686578655665448478657834657533335544343231212251101
+200144235323636235437557635373578555545475587655886585897998654658858755534374677344254563233421200
+433243323452635426237436445738684446475489658878699879887988684656474746764334543334452565153341241
+340411231113223465344733555465744685569658998876796578688888887678657675875533766464362432543531231
+132155112416452662274535754677457567869597559977756878779755568868854644586734466764422245333151550
+321153454153653654743477667888756477986578656976558879999589975695487876766664653466625262642234421
+414524133155254243564664555445778475666688565697596679558768656758547564888437343772346336642515514
+321251321324554554436434474754674597576658986766997798688766897876884764444653674674326233445555243
+031553412663524646375654566887688857698655696699699989968699659665774657875735457664452362352111522
+121541141642244257534355645887786995858959886778688769889987779898696567777567344373632655621545545
+334343242432423553675774445756455759676757789677879778999988695976997447856786357655446656351514552
+125145532643224566754564678556569669557567799868776897666898866898879866784847777744353546366314141
+045114213352452647446647465888875868689699789677897977779999699895556776458746737674746244442322442
+132343555663565436365447746478789879798676878686777999789966769777759954677478745673552645533545344
+045253354653642556466557766588567888887978866878777776986676768968695857655674556463732652626443441
+324411423536354677366485874488885578788769789998797978797888777868996895476778847746764226464355343
+355421453642352476436787475855785669696986976979989787787998669696679989555875747556435562425323311
+225422326356526465747344444546866698678986799879779799999876866969999686664477767757535635652555421
+215234242322226376376776764668889755898766677787987779877967696689565966757675463574434246652622343
+214252444222333767567367778585695867987669688798987987789888698888858597545545475573737453632634414
+435144324646623745547785547465689576878976877888878988989877866686976879488454664357347554642541254
+424224446333664566656688545685586987987699788897978888788999878967887869445474863534753362524653532
+234521532264544735666677658457578679997886798878788998987976677895559685784445835563745433436535545
+541253562333326733576345574569866788667878789897999998887996866685657897848485475437744246636412312
+531515163362265375476387485646556857878999799999999989879989886696789765664474863474462523344554532
+134323536435565375644658845476675857999867789999988888799986676978987577885467643356656525623333421
+432434326635433776557758756889896978587689688777989999797796888999765958586488873373565325435254453
+352344243543664654777655867556767767686778796989888798998697976755779565488844544677343523234525134
+023522455223435563774634466685769765877876776996699877886876668865856964846675357575675235445525211
+452211123455454466574537744568597875596879779869788776669767986968956557448486336534544244456115451
+154255352645344566574476875484685575595898898697799799688669879869766768688476473673634645556554324
+153224532366353377543578485765465665577767776999977978876879865565957587758448456773452265664315213
+212223354662352476456344644856876756566976677698968768897897866997679566845464663374352444344522513
+333134124655526377555445475778655559695856687767878889687866969787796886748547665457422543622531314
+114114243655626456537464558857564557866777897897898988696885586978887448448543375665233363532515252
+022123225426235336675765546686448888566865666569876966556979869667956845877753374733454555422452344
+105112231544246463366336777688875488697685796985999888976956985978664485756743456372244565641412542
+243421525526425322655767646868764584599579555769857975877669799998745668566534743565233224245452434
+310412235133463356343754335447454467578555798898788997569756589585876868467475435524433556255213522
+122253434533466554567356664688567676567976599967878669868967997845484546736534545734455626245154423
+313334534424352263526466637778587787868565658999559897596678677574858776343543534432632333531241224
+001031252124265545567437743765668445564487997555965858678954577555545545743366457636433553523254344
+044305452425444342246365565576568644874888888677955886697487686854588744354437555336664241413533111
+110113123534526242542645447354547688467557884774478677887477777586654656653436654455626314334324023
+403311355254242426345425533745657486754657454674877454647844866774463676664344325662334351444144012
+114043453225323265365363357353773386544675474785655464585675566555543364665665355442555535443420344
+234021355512324262426566274773756436677647664566764646854655875476556464746532226425352124354233001
+104234323224222234534254555373773666356744475886877868685764755374634533664662562645321154355101301
+413312132345313224565423553463467666456365585778746647466885776356666677636556254365513311121044324
+010140223145323354554344523347476477547564757555585887484666633663433654743326266555221322431333120
+023311233225342421354662654347733666374666336373663635367447753577353743232632663243333251551031321
+143043334422453221246324462653756444767736544367544755375437335646557334655533644454121143303220002
+101212344011254432246625336226267546745356655577456676377355677475746633565634244145133154032123242
+233244204414154431434433222525444454344635736634774576466473546373725623264634363324244114303014300
+010103422332213512154554324533443662535535356636747655647737636354525554536436123454141421414030443
+203123300244432323224135253642444433566335637575443374634433336553444225543564152215332533001133230
+213003230312403552352142145445635666323653353353657647435752235322633623453542112525124011312421020
+120004434213011143254452233425222536464236356544634635324242345464353322232141135221424123200431123
+331000214011314431233211121223425334456246345226324246526344536556636556453143153253323114441131132
+303123142412333143322451153243464566344362342525524265432552566442626262524431454151443133021301210
+220100102032004440315125323552226234566265233246334556355333643662354455122325544112124232340231031
+112122312031202424345533512342151435534325334444254264542526645645533111234131131223411304322200110
+213031212133401330114433121533455425225634422363334633454623522242353342455454511303033230433202120
+223232022333401311421344332255311133421254642562465526534445512134533413153142410113101444330132130
+020133013100324344342244215442123125243314222446342424421353134352515124333133430431401122202211032
+102300310001014311443112031115242425132234255215315523551534154524134344433432201022200432133000302
+001233311232134334100401400151532231322435145412132433235254313414243334103312232304403111313321210
+110213022233310011220103432114343112114222424442543155552411511144115122143322304023012132213011210
+000220123220323122321103444304134551331233141552114422121151224211122042434324042030120133230110110
+020120232301110331441234422110132302233413123211331413433254521355004032312110222131010330301222211

day08/test.txt

@@ -0,0 +1,5 @@
+30373
+25512
+65332
+33549
+35390

flake.nix

@@ -13,6 +13,7 @@
       day05 = pkgs.callPackage ./day05 { };
       day06 = pkgs.callPackage ./day06 { };
       day07 = pkgs.callPackage ./day07 { };
+      day08 = pkgs.callPackage ./day08 { };
     };
   };
 }