diff --git a/2021/day19.hs b/2021/day19.hs
new file mode 100644
index 0000000..337e4d9
--- /dev/null
+++ b/2021/day19.hs
@@ -0,0 +1,98 @@
+module Day19 where
+import Data.List.Split (splitOn)
+import Debug.Trace (trace, traceShow)
+import Data.List (delete, transpose, maximumBy, sort, nub)
+import Data.Ord (comparing)
+import qualified Data.Bifunctor
+
+type Coord = (Int,Int,Int)
+
+add :: Coord -> Coord -> Coord
+add (x,y,z) (a,b,c) = (x+a, y+b, z+c)
+
+readScanner :: [String] -> [Coord]
+readScanner [] = error "empty scanner"
+readScanner (x:xs) = map pos xs where
+    pos line = (x,y,z) where [x,y,z] = map read $ splitOn "," line
+
+-- shamelessly stolen from spoiler
+transformCoord :: Coord -> [Coord]
+transformCoord (x,y,z) = [
+        (x,y,z),
+        (-x,-y,z),
+        (-x,y,-z),
+        (x,-y,-z),
+        (y,z,x),
+        (-y,-z,x),
+        (-y,z,-x),
+        (y,-z,-x),
+        (z,x,y),
+        (-z,-x,y),
+        (-z,x,-y),
+        (z,-x,-y),
+        (x,z,-y),
+        (x,-z,y),
+        (-x,z,y),
+        (-x,-z,-y),
+        (y,x,-z),
+        (y,-x,z),
+        (-y,x,z),
+        (-y,-x,-z),
+        (z,y,-x),
+        (z,-y,x),
+        (-z,y,x),
+        (-z,-y,-x)]
+
+deltas :: [Coord] -> [(Coord, [Coord])]
+deltas coords = map (\c -> (c, deltas' c)) coords where
+    deltas' c = map (delta c) (c `delete` coords)
+    delta (x,y,z) (a,b,c) = (x-a, y-b, z-c)
+
+findOverlap :: [Coord] -> [Coord] -> [Coord]
+findOverlap sc1 sc2 = map fst $ filter (in2 . snd) d1 where
+    d1 = deltas sc1
+    d2 = concatMap snd (deltas sc2)
+    in2 c = any (`elem` d2) c
+
+maxi :: (Ord a1) => [a1] -> (a1, Int)
+maxi xs = maximumBy (comparing fst) (zip xs [0..])
+
+merge :: ([Coord], [Coord]) -> ([Coord], [Coord]) -> ([Coord], [Coord])
+merge (diffs, known) (overlappingNew, scanner) = (diff:diffs, nub $ sort $ known ++ map (add diff) scanner) where
+    overlappingOrig = findOverlap scanner known
+    diff = (x-nx, y-ny, z-nz) where (x,y,z) = minimum overlappingNew; (nx,ny,nz) = minimum overlappingOrig
+
+
+discover :: [Coord] -> [Coord] -> [[[Coord]]] -> ([Coord], [Coord], [[[Coord]]])
+discover diffs known [] = (diffs, known, [])
+discover diffs known aux = trace ("total: " ++ show (length newKnown) ++ "; best: " ++ show (map (length.fst) bestPer)) $
+                            if bestScore < 12 then (diffs, known, aux) else (diffs ++ fst newKnown, snd newKnown, newAux) where
+    overlapKnown = map (map (\x -> (findOverlap known x, x))) aux
+    bestPer = map (maximumBy (\x y -> compare (length $ fst x) (length $ fst y))) overlapKnown
+    bestScore = maximum $ map (length . fst) bestPer
+    scanners = filter (\scanner -> length (fst scanner) >= 12) bestPer
+    newKnown = foldl merge ([], known) scanners
+    newAux = filter (\s -> all ((`notElem` s) . snd) scanners) aux
+
+discoverUntil :: [Coord] -> [Coord] -> [[[Coord]]] -> ([Coord], [Coord], [[[Coord]]])
+discoverUntil diffs known aux = if known == known' then (diffs', known', aux') else discoverUntil diffs' known' aux' where
+    (diffs', known', aux') = discover diffs known aux
+
+manhattan :: Coord -> Coord -> Int
+manhattan (a,b,c) (x,y,z) = abs (a-x) + abs (b-y) + abs (c-z)
+
+main :: IO ()
+main = do
+    input <- map readScanner . splitOn [""] . lines <$> getContents
+
+    let known = head input
+    let aux = transpose $ map (\i -> map (map (\c -> transformCoord c !! i)) (tail input)) [0..23]
+
+    let (diffs, final, aux') = discoverUntil [] known aux
+
+    putStr "part 1: "
+    print $ length final
+
+    putStr "part 2: "
+    let manhattans = concatMap (\s -> map (manhattan s) diffs) diffs
+    print $ maximum manhattans
\ No newline at end of file
diff --git a/2021/inputs/day19.input b/2021/inputs/day19.input
new file mode 100644
index 0000000..534b6f5
--- /dev/null
+++ b/2021/inputs/day19.input
@@ -0,0 +1,717 @@
+--- scanner 0 ---
+-610,495,658
+619,646,813
+824,672,-795
+46,-39,48
+417,571,821
+-805,453,-303
+-888,396,-338
+-476,-659,-760
+-565,451,589
+-360,-695,-736
+747,682,-698
+-640,-788,852
+-456,499,642
+-639,-860,768
+755,-706,572
+-510,-763,-684
+326,-630,-599
+486,672,902
+426,-582,-537
+773,654,-588
+-484,-887,839
+395,-595,-768
+-735,509,-330
+735,-629,606
+810,-851,608
+
+--- scanner 1 ---
+691,-615,-596
+459,-820,345
+727,421,-583
+-504,778,-728
+-304,-931,507
+680,257,604
+105,-55,-128
+625,275,720
+-490,654,-884
+547,-713,263
+722,381,-665
+587,-500,-582
+723,-543,-526
+-324,402,601
+-706,-573,-643
+566,303,707
+687,485,-677
+-382,-788,510
+-8,-168,-10
+408,-812,285
+-852,-572,-742
+-395,727,-808
+-378,372,416
+-793,-676,-748
+-364,-872,401
+-455,385,572
+
+--- scanner 2 ---
+-630,539,-832
+453,-736,716
+-620,-486,518
+409,-817,634
+340,-827,665
+390,847,-459
+343,713,-531
+-730,-493,648
+449,614,601
+-862,-862,-324
+-33,-19,15
+507,583,604
+-562,629,-717
+-396,674,378
+656,-758,-378
+-775,-556,549
+386,595,-469
+619,-844,-379
+-529,509,-821
+-331,644,348
+-906,-785,-305
+-877,-919,-415
+584,584,578
+-444,785,330
+587,-926,-418
+
+--- scanner 3 ---
+789,696,-627
+-434,-942,427
+-333,613,529
+758,626,-782
+-323,716,-425
+907,-683,654
+591,446,446
+766,-789,-704
+673,365,402
+34,11,-117
+-347,-799,419
+154,-87,57
+-309,569,-489
+773,-813,-798
+-287,606,-505
+-601,-856,-467
+659,689,-737
+895,-719,864
+-666,-833,-413
+944,-718,635
+-445,-937,366
+-731,-759,-465
+-491,676,498
+-470,608,672
+642,355,333
+794,-861,-887
+
+--- scanner 4 ---
+-594,-270,766
+-18,91,75
+-408,-554,-590
+-496,427,605
+787,-666,849
+-541,-326,669
+590,914,-478
+-607,-251,615
+819,-259,-460
+-613,-589,-554
+675,-271,-532
+566,411,590
+680,457,487
+699,-559,931
+578,911,-741
+-506,-436,-520
+838,-658,909
+815,-307,-557
+621,429,474
+-794,879,-625
+-440,554,550
+-660,890,-528
+-791,864,-664
+-556,410,584
+543,956,-616
+
+--- scanner 5 ---
+-175,44,-29
+800,604,736
+-600,591,-761
+-665,-613,322
+349,440,-453
+-818,-516,-844
+699,-529,-374
+-755,-545,437
+708,-480,-508
+-499,490,-693
+-843,-572,-909
+284,512,-486
+526,-505,-423
+-805,-538,-751
+-20,-22,55
+-839,360,623
+632,673,776
+793,-860,739
+659,-889,849
+-973,407,695
+-721,403,685
+736,-845,830
+718,636,775
+319,535,-369
+-606,618,-669
+-635,-512,333
+
+--- scanner 6 ---
+-316,579,-312
+-297,-790,-711
+-348,-730,-719
+435,-474,503
+607,833,578
+-557,860,858
+-436,-812,-612
+415,-568,-830
+53,112,121
+698,887,-370
+657,774,487
+566,-503,486
+-455,-368,404
+816,926,-466
+-569,-471,358
+-545,597,861
+741,896,506
+-320,676,-360
+821,807,-428
+-514,-355,376
+-460,651,-324
+-592,735,903
+151,164,-31
+475,-674,-771
+489,-659,473
+493,-565,-687
+
+--- scanner 7 ---
+435,557,-655
+-770,550,-327
+-699,515,-271
+-577,-446,442
+451,-860,586
+-808,647,655
+637,-442,-503
+-567,-543,519
+280,262,615
+319,360,662
+-937,-885,-798
+-733,621,601
+-650,645,652
+801,-410,-429
+-66,-68,143
+537,711,-636
+297,271,557
+-595,-653,493
+773,-436,-359
+341,-912,565
+478,737,-709
+-696,352,-330
+411,-845,593
+-849,-848,-800
+-698,-875,-797
+
+--- scanner 8 ---
+-664,-627,704
+-841,494,-595
+652,-801,406
+-862,425,-585
+637,459,554
+530,-629,-385
+-515,697,751
+691,487,683
+-552,-681,-615
+686,-801,451
+-552,720,692
+-634,-725,-696
+-603,-794,-706
+298,374,-483
+-690,-550,705
+509,-455,-453
+316,454,-362
+326,504,-379
+372,-598,-448
+-583,833,701
+540,-833,430
+-59,-49,80
+645,513,567
+-667,-685,735
+-848,556,-701
+
+--- scanner 9 ---
+414,487,-749
+-680,-624,-479
+-67,-57,-44
+484,-790,-397
+583,522,-818
+816,-659,919
+-706,-549,-533
+621,282,721
+826,-420,920
+-714,346,-731
+-704,-707,-530
+-665,637,422
+668,240,583
+594,-762,-371
+-574,-658,393
+645,474,-718
+633,285,458
+3,-121,131
+387,-780,-320
+-829,281,-756
+-581,656,544
+-531,565,485
+789,-508,922
+-609,-587,449
+-411,-661,452
+-890,366,-746
+
+--- scanner 10 ---
+-627,-609,-816
+-591,-495,-690
+-585,-502,631
+-650,814,782
+-858,529,-758
+380,305,-577
+-647,671,704
+444,-523,-703
+751,-594,590
+-31,-131,-124
+-756,755,722
+-745,551,-609
+319,-487,-616
+452,488,-605
+725,412,376
+844,450,381
+-826,591,-589
+692,-503,540
+-575,-442,-752
+428,394,-598
+361,-474,-773
+-741,-489,708
+805,354,499
+-556,-519,762
+814,-522,456
+
+--- scanner 11 ---
+-838,-676,-466
+511,284,707
+52,-49,-52
+-742,-794,-427
+-504,423,318
+416,368,677
+612,-860,308
+-127,-13,-146
+-848,342,-677
+542,-744,-631
+-884,-824,233
+-913,-934,367
+645,433,-888
+-884,482,-702
+649,-861,394
+-780,-799,-546
+558,-658,-628
+-896,338,-774
+-869,-915,290
+488,401,742
+-529,338,500
+771,421,-767
+620,490,-741
+580,-821,226
+479,-690,-459
+-553,289,327
+
+--- scanner 12 ---
+-717,579,534
+766,749,-954
+177,64,26
+666,686,530
+-672,728,-741
+-604,548,543
+632,-727,-468
+949,-544,805
+-684,-574,-532
+-371,-695,552
+671,-668,-552
+801,663,500
+-343,-641,681
+661,-697,-616
+-643,670,-662
+99,-14,-127
+852,697,-857
+917,-690,784
+-397,-649,668
+883,593,-939
+-5,128,-65
+-639,-550,-476
+-581,511,484
+743,660,531
+917,-656,829
+-686,703,-802
+-637,-530,-607
+
+--- scanner 13 ---
+-326,-746,-526
+753,-765,472
+-329,-483,-514
+710,500,848
+-284,-608,-479
+570,-829,453
+-518,693,-502
+19,28,139
+-361,-599,858
+615,-944,-331
+-566,793,-564
+-350,-696,724
+-642,364,607
+-787,309,643
+746,372,-663
+-531,724,-733
+712,-877,524
+736,295,-760
+109,-158,-31
+635,702,856
+718,346,-553
+376,-945,-321
+736,633,937
+-376,-560,855
+-565,384,641
+464,-947,-358
+
+--- scanner 14 ---
+287,538,833
+456,-658,-332
+649,-664,559
+-499,651,634
+437,470,781
+566,373,-671
+338,-640,-388
+-676,-568,-309
+-682,-426,-329
+-855,-673,936
+-682,-697,887
+567,445,-755
+687,-630,401
+662,-686,466
+411,346,-742
+-57,-87,160
+-828,527,-475
+4,86,-14
+350,-743,-361
+-399,603,696
+-808,604,-509
+-468,638,865
+-772,-547,-416
+403,574,857
+-883,382,-511
+-864,-722,802
+
+--- scanner 15 ---
+469,-858,324
+693,669,-643
+-397,-551,-564
+478,-668,303
+157,-16,-98
+-447,698,716
+-377,729,561
+439,-707,-392
+692,643,-566
+-2,74,-8
+753,899,272
+-467,-347,439
+723,646,-508
+-504,-369,423
+-708,613,-468
+461,-644,388
+894,917,385
+783,869,337
+-460,-393,-595
+-384,599,671
+-465,-530,-738
+-718,582,-399
+-627,531,-512
+-357,-383,359
+394,-673,-392
+418,-561,-360
+
+--- scanner 16 ---
+663,520,581
+-790,410,759
+429,-660,365
+-840,596,-622
+700,-660,-851
+-379,-459,547
+333,614,-851
+-816,546,628
+550,-570,452
+-524,-514,511
+-648,-843,-598
+66,-103,36
+-601,-534,545
+571,-666,345
+-600,-943,-660
+345,542,-707
+628,484,376
+-882,458,-575
+-635,-874,-829
+-98,-25,-89
+381,517,-847
+510,554,474
+-837,333,-610
+676,-487,-900
+725,-478,-766
+-805,449,762
+
+--- scanner 17 ---
+574,-491,651
+537,816,632
+521,665,-272
+-630,560,-520
+-370,-583,-408
+444,822,542
+675,-414,640
+-631,382,-571
+636,-494,-690
+662,670,-394
+-47,-16,78
+-653,356,-528
+-367,-635,410
+-351,-438,-486
+669,670,-300
+-324,-507,464
+585,-397,-567
+593,-418,678
+-658,603,839
+-416,-570,-482
+-368,-478,428
+562,-544,-547
+411,832,763
+-721,643,761
+-672,451,760
+
+--- scanner 18 ---
+581,674,-678
+-850,707,-718
+814,-386,-737
+-877,-306,-508
+550,677,-620
+-718,-253,783
+-860,738,-787
+538,789,727
+-739,479,432
+409,-219,436
+597,826,704
+-712,-444,690
+562,-396,-741
+438,-264,382
+-791,-305,-471
+680,-458,-784
+-959,-345,-540
+-90,118,131
+-769,789,-674
+-855,493,563
+-18,-7,-47
+551,651,-543
+547,758,840
+-632,-391,788
+-749,500,501
+447,-419,482
+
+--- scanner 19 ---
+-476,-439,905
+633,600,635
+-583,-527,987
+52,-52,78
+-365,324,743
+492,621,-719
+498,-427,608
+766,657,691
+784,-490,-411
+571,589,-550
+-883,-407,-404
+-484,-388,965
+555,675,-547
+776,598,490
+379,-429,438
+-871,-551,-476
+-835,-411,-501
+-729,725,-751
+-825,607,-712
+-767,730,-632
+658,-502,-290
+633,-559,-437
+334,-462,592
+-424,384,849
+-508,402,740
+
+--- scanner 20 ---
+590,-944,-534
+475,296,714
+-735,-479,-428
+456,418,630
+-355,-394,819
+746,-872,939
+-326,-528,929
+-343,613,-343
+-459,385,794
+-391,516,-347
+830,595,-572
+625,-875,-365
+766,-857,763
+-370,-451,910
+-355,541,-487
+638,-844,-596
+827,332,-584
+872,457,-619
+-401,305,671
+-497,266,789
+-686,-488,-294
+80,-56,98
+547,359,580
+-60,-91,-46
+831,-882,878
+-710,-661,-343
+
+--- scanner 21 ---
+374,727,-469
+508,655,-422
+504,-877,510
+-350,604,-754
+747,-729,-653
+-258,573,-801
+-712,-467,-629
+-715,-591,-772
+592,469,483
+-757,-666,590
+-683,-594,537
+682,354,551
+741,-637,-680
+848,-661,-552
+-616,716,435
+106,90,-59
+712,365,450
+-9,-37,39
+-549,657,492
+-641,-565,597
+-407,652,-862
+-679,-594,-517
+529,-812,454
+626,717,-465
+-587,738,431
+542,-719,476
+
+--- scanner 22 ---
+-434,572,693
+-527,-427,869
+697,410,-675
+583,-761,494
+812,308,570
+-655,-470,923
+-498,-471,905
+-511,471,682
+-552,260,-484
+-564,-942,-373
+513,-641,-413
+560,-506,-520
+682,491,-679
+623,-824,572
+796,434,701
+-570,-751,-466
+54,-67,182
+-520,448,-474
+-665,368,-500
+802,341,791
+717,558,-804
+-438,490,655
+546,-727,-464
+-650,-804,-368
+-85,-160,55
+431,-775,573
+
+--- scanner 23 ---
+466,697,-742
+-453,-516,611
+288,626,597
+573,-781,-775
+438,769,-925
+-54,-38,-158
+459,721,-836
+-520,305,-780
+-515,424,-818
+-638,344,-876
+-380,-489,-951
+-570,509,504
+443,-788,-665
+325,591,616
+-624,337,441
+641,-538,408
+559,-457,364
+-656,506,520
+337,627,826
+-454,-430,574
+-493,-348,542
+474,-718,-820
+-490,-355,-922
+590,-447,295
+-399,-412,-907
+
+--- scanner 24 ---
+-705,508,-364
+483,-792,588
+-521,-543,-626
+-554,-629,-575
+-370,-621,758
+-539,-589,679
+-568,-408,-519
+315,-752,657
+-652,559,617
+562,-653,-573
+-690,589,-360
+26,-59,116
+831,470,749
+512,546,-565
+657,466,-539
+-678,490,466
+-799,502,592
+766,437,821
+796,353,726
+-542,-675,695
+556,-844,-666
+544,358,-555
+-725,656,-235
+397,-791,625
+642,-706,-671
+
+--- scanner 25 ---
+-549,544,757
+24,-9,-115
+-652,560,-521
+-326,-827,581
+-746,553,-497
+-611,713,789
+706,419,-627
+-728,-421,-794
+-385,-767,687
+-835,532,-449
+-690,-426,-913
+805,-494,529
+-589,564,676
+594,-476,-709
+-469,-749,578
+551,890,246
+687,382,-592
+527,881,472
+-786,-544,-874
+610,-562,-712
+916,431,-591
+531,-530,-881
+815,-553,328
+497,886,320
+672,-551,473
\ No newline at end of file
diff --git a/2021/inputs/day19.sample b/2021/inputs/day19.sample
new file mode 100644
index 0000000..4e496e9
--- /dev/null
+++ b/2021/inputs/day19.sample
@@ -0,0 +1,136 @@
+--- scanner 0 ---
+404,-588,-901
+528,-643,409
+-838,591,734
+390,-675,-793
+-537,-823,-458
+-485,-357,347
+-345,-311,381
+-661,-816,-575
+-876,649,763
+-618,-824,-621
+553,345,-567
+474,580,667
+-447,-329,318
+-584,868,-557
+544,-627,-890
+564,392,-477
+455,729,728
+-892,524,684
+-689,845,-530
+423,-701,434
+7,-33,-71
+630,319,-379
+443,580,662
+-789,900,-551
+459,-707,401
+
+--- scanner 1 ---
+686,422,578
+605,423,415
+515,917,-361
+-336,658,858
+95,138,22
+-476,619,847
+-340,-569,-846
+567,-361,727
+-460,603,-452
+669,-402,600
+729,430,532
+-500,-761,534
+-322,571,750
+-466,-666,-811
+-429,-592,574
+-355,545,-477
+703,-491,-529
+-328,-685,520
+413,935,-424
+-391,539,-444
+586,-435,557
+-364,-763,-893
+807,-499,-711
+755,-354,-619
+553,889,-390
+
+--- scanner 2 ---
+649,640,665
+682,-795,504
+-784,533,-524
+-644,584,-595
+-588,-843,648
+-30,6,44
+-674,560,763
+500,723,-460
+609,671,-379
+-555,-800,653
+-675,-892,-343
+697,-426,-610
+578,704,681
+493,664,-388
+-671,-858,530
+-667,343,800
+571,-461,-707
+-138,-166,112
+-889,563,-600
+646,-828,498
+640,759,510
+-630,509,768
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+
+--- scanner 3 ---
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+
+--- scanner 4 ---
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