Day 13

Setup

Mix.install([
  {:kino, "~> 0.4.1"}
])

Example input: ``` 6,10 0,14 9,10 0,3 10,4 4,11 6,0 6,12 4,1 0,13 10,12 3,4 3,0 8,4 1,10 2,14 8,10 9,0 fold along y=7 fold along x=5 ``` Real input: ``` 1141,761 175,114 628,854 654,506 314,266 370,883 642,826 244,669 739,429 970,852 1298,740 1121,777 642,579 497,308 1150,460 644,60 745,866 1169,882 807,338 319,705 740,647 763,632 1163,829 1278,408 460,675 1002,301 162,550 243,353 858,240 632,372 704,749 604,494 917,240 1034,838 261,800 585,238 741,39 315,674 1298,803 189,117 606,184 797,348 244,144 1290,110 1198,54 459,192 401,868 70,217 1077,54 634,110 982,660 179,737 1221,5 49,810 223,423 760,600 170,42 679,380 658,793 78,625 1036,283 995,674 353,225 1032,525 735,353 140,372 333,830 609,410 900,213 154,817 218,667 726,217 258,268 502,889 654,424 237,677 499,870 995,686 1265,238 112,795 32,30 1230,682 734,625 539,208 353,221 1019,292 324,236 137,22 1148,176 44,320 482,350 761,95 276,838 1266,320 172,749 976,194 480,584 403,144 172,593 1044,283 406,255 150,0 545,488 195,416 1299,226 140,820 569,855 345,290 962,723 35,816 426,542 524,103 92,392 587,336 358,235 321,474 666,39 1115,478 479,444 15,441 79,317 112,54 62,313 972,248 524,299 1096,270 851,702 1262,184 554,856 363,78 850,637 87,592 152,5 1153,581 185,98 1135,114 1231,317 398,390 524,567 68,402 398,838 108,756 216,78 425,256 1029,500 1099,763 20,784 410,681 544,567 636,166 196,103 971,208 821,432 1180,810 893,553 1146,12 223,726 141,418 340,467 269,35 195,478 572,254 132,616 62,718 472,525 656,449 611,894 1098,110 1089,799 18,276 258,402 1136,423 1158,808 324,460 89,341 308,288 334,700 1221,30 634,499 517,565 763,665 314,822 11,226 1091,184 142,171 644,453 537,298 62,176 684,16 294,38 179,1 1160,894 1174,644 1180,82 776,520 1173,872 744,348 1057,196 1298,826 1150,152 950,455 1300,60 460,616 932,614 984,22 252,331 455,372 922,199 88,409 564,631 970,315 182,2 572,634 408,234 632,624 1221,530 48,184 401,26 1014,464 1128,444 1233,290 446,521 47,880 238,369 407,465 1006,423 1087,23 1009,511 723,663 1278,439 867,131 1009,665 1198,99 97,61 539,238 1153,26 642,875 141,882 32,590 705,138 343,453 1180,586 340,180 70,504 681,872 408,820 652,182 1158,310 1098,784 73,840 1116,21 348,483 756,515 23,514 1028,460 1169,12 1292,276 554,515 850,271 50,481 455,66 674,584 940,883 813,586 454,227 718,46 2,854 1032,822 1087,471 1046,304 1180,308 136,698 584,108 796,731 244,449 781,714 726,677 278,749 22,522 421,432 996,822 1134,178 345,738 913,726 413,66 1213,61 182,749 353,847 738,260 1059,368 12,154 1058,331 1046,269 937,36 765,854 169,26 1228,549 682,40 875,632 223,471 874,530 1026,883 996,427 194,257 952,847 900,640 880,200 8,151 1262,145 546,152 1012,729 955,9 1282,873 1016,663 850,392 725,656 139,523 592,189 934,525 1168,171 412,423 1057,474 299,457 388,361 127,828 828,145 1041,35 909,478 776,374 1094,791 398,120 502,23 783,527 1140,42 1180,327 80,660 376,749 1086,240 994,23 276,280 716,247 1202,756 406,471 282,96 967,441 1015,864 67,663 472,640 166,658 507,513 28,21 1195,686 1192,863 848,148 330,199 453,714 130,586 1072,185 150,296 238,33 989,420 1278,887 281,52 338,248 763,229 283,218 738,449 575,353 1169,418 957,221 658,854 597,351 721,352 723,336 964,86 857,712 155,306 78,191 469,12 1243,663 162,718 281,500 975,306 393,58 637,828 80,522 246,717 308,606 229,256 462,820 1138,593 830,584 950,142 495,711 852,187 130,362 147,289 1228,345 671,673 1077,432 1064,32 684,878 960,148 984,458 32,439 1141,313 264,269 257,616 229,638 1290,784 718,257 1201,40 314,803 458,856 1305,382 658,773 995,220 321,469 1202,667 850,278 920,403 1124,494 808,711 989,425 927,856 1178,891 594,199 897,150 462,522 331,184 1230,1 601,70 150,436 241,150 994,616 932,280 226,248 10,386 1184,3 196,327 388,199 169,133 745,476 460,392 1173,777 390,624 939,560 855,66 360,142 1096,504 529,462 479,562 932,736 155,446 234,724 277,308 1225,514 224,654 745,478 38,21 581,812 89,364 770,570 62,189 970,266 991,189 864,521 806,296 494,12 488,152 333,64 489,208 130,327 1155,870 84,647 1014,399 975,474 1223,512 184,134 1054,665 831,444 1016,38 678,522 1078,721 1009,217 406,647 90,77 726,786 547,297 201,462 296,430 436,227 109,40 170,465 663,588 957,225 594,647 1185,740 654,449 656,470 1265,208 566,348 363,623 1191,387 676,395 749,450 1114,595 1029,52 1232,255 735,541 79,129 223,23 639,889 152,808 783,197 211,315 745,418 831,450 524,595 619,826 1135,780 315,686 515,371 415,64 746,631 584,217 281,394 1140,465 658,121 678,372 110,359 636,614 806,514 976,602 1067,541 176,716 977,64 565,866 606,749 1136,584 107,665 534,520 233,462 460,502 484,877 1163,320 718,332 753,833 725,238 1033,455 346,86 489,432 796,176 1267,222 825,138 1163,737 1308,40 201,656 458,187 592,562 489,462 1174,196 372,544 1170,372 196,366 266,695 1173,341 1193,298 10,229 88,537 295,30 904,647 132,425 569,156 782,3 176,436 965,290 768,383 877,543 372,350 846,82 125,742 537,148 48,145 783,828 572,445 960,199 1064,673 194,189 1007,66 1222,546 1125,12 1002,512 990,521 380,428 1033,308 1262,301 137,777 1007,514 1216,91 1019,602 920,637 12,91 811,870 678,270 637,66 433,799 311,217 320,521 1148,434 999,217 232,49 164,348 908,563 1158,584 810,525 1123,371 1305,512 688,864 581,474 118,863 115,686 169,138 1202,308 950,612 405,290 709,70 514,74 933,719 182,166 257,278 1014,430 855,25 831,780 517,374 522,469 841,546 1225,738 393,352 1004,171 348,275 321,873 1183,645 826,877 574,269 1275,714 473,156 472,702 766,77 756,422 1298,852 698,201 1028,3 485,868 1265,656 397,726 1173,117 335,420 364,373 1302,151 438,499 502,871 78,177 416,369 745,665 1039,589 793,872 619,154 540,150 147,605 428,198 1169,866 870,105 162,270 781,462 989,469 884,542 478,884 585,656 1131,605 278,374 1087,423 1150,882 334,373 1272,333 970,467 70,56 580,115 69,392 1081,190 1265,110 36,499 996,803 934,749 920,38 112,511 534,374 938,891 1185,152 412,247 676,110 584,675 438,807 1151,183 186,400 673,66 668,292 12,852 574,669 976,373 306,275 390,403 585,315 378,614 576,625 1205,799 350,746 410,445 678,471 549,95 838,192 852,856 319,637 301,511 402,563 339,504 1057,698 62,637 340,315 1076,724 350,563 596,294 771,238 766,499 731,816 278,822 1073,677 562,284 80,372 382,112 57,543 351,66 996,290 1284,406 350,695 1251,726 1029,36 1292,618 517,553 1111,372 584,677 192,372 80,682 808,423 982,458 380,466 199,372 937,708 1128,2 736,625 699,894 897,156 552,311 885,256 1126,134 570,647 458,528 1222,409 725,635 783,380 990,821 1288,423 979,710 502,392 176,290 605,138 557,14 25,673 912,838 1292,584 1298,68 117,298 43,222 967,453 619,740 1062,639 1156,369 544,87 736,269 623,416 5,382 990,292 995,838 649,606 984,872 1051,231 585,635 1298,763 584,56 492,792 686,11 176,604 1275,290 884,654 636,469 147,829 10,646 1300,647 738,254 572,885 507,829 132,54 253,196 373,558 1210,38 504,458 1202,152 194,873 1114,366 632,23 1028,96 89,553 550,600 1068,23 315,838 249,514 897,828 980,695 130,103 401,478 492,434 174,871 416,525 725,315 902,234 196,856 1198,392 587,112 729,474 848,201 609,574 320,821 879,726 1196,598 1016,243 547,665 957,677 12,68 1160,296 1192,339 542,789 524,532 957,453 196,812 726,338 1230,458 642,315 233,483 1180,84 579,176 62,332 246,32 316,229 507,65 691,156 0,470 517,872 644,199 462,201 1155,448 584,838 652,121 314,467 1148,718 893,341 1300,732 818,434 79,577 1222,357 1094,103 619,738 530,449 195,192 311,677 1062,717 28,873 98,206 855,372 726,838 666,199 666,453 972,646 462,74 196,775 1125,98 1248,241 938,350 416,33 1138,301 1114,775 1141,26 1010,194 745,28 816,12 1049,94 291,719 996,490 904,255 704,184 1210,422 184,187 889,462 514,176 783,514 1282,21 130,632 1310,469 786,595 714,152 20,499 989,474 119,387 1016,231 808,392 907,144 390,270 12,292 888,49 248,269 1081,208 1146,98 174,584 798,723 385,859 314,490 1032,374 850,257 915,231 59,168 395,231 182,254 774,443 1073,665 304,695 1288,522 549,799 1248,176 1178,54 725,392 1163,289 1072,369 115,656 622,243 294,231 831,562 169,581 110,395 1186,295 502,616 1222,537 320,73 530,239 110,87 338,487 1009,246 647,868 1067,353 671,221 196,408 632,270 10,647 649,830 1169,236 243,541 1077,483 0,506 1069,828 223,168 1012,654 922,533 766,359 1178,425 185,796 1200,87 1228,254 353,677 50,606 306,171 108,152 1248,313 938,3 1221,364 738,640 813,698 1174,698 425,704 38,469 43,672 1279,416 fold along x=655 fold along y=447 fold along x=327 fold along y=223 fold along x=163 fold along y=111 fold along x=81 fold along y=55 fold along x=40 fold along y=27 fold along y=13 fold along y=6 ```

input = Kino.Input.textarea("Puzzle Input")

Process Input

lines =
  input
  |> Kino.Input.read()
  |> String.split("\n", trim: true)

points =
  for line <- lines,
      String.match?(line, ~r/^\d/),
      do: line |> String.split(",") |> Enum.map(&String.to_integer/1) |> List.to_tuple()

folds =
  for line <- lines,
      String.match?(line, ~r/^fold/),
      do:
        line
        |> String.split()
        |> Enum.at(2)
        |> String.split("=")
        |> then(fn [axis, value] -> {axis, String.to_integer(value)} end)

:ok

Part 1 first try

[{fold_axis, fold_value} | _] = folds

if fold_axis == "x" do
  Enum.map(points, fn {x, y} ->
    if x > fold_value, do: {fold_value * 2 - x, y}, else: {x, y}
  end)
else
  Enum.map(points, fn {x, y} ->
    if y > fold_value, do: {x, fold_value * 2 - y}, else: {x, y}
  end)
end
|> Enum.uniq()
|> Enum.count()

Letters

letters = %{
  [
    {0, 1, 1, 0},
    {1, 0, 0, 1},
    {1, 0, 0, 1},
    {1, 1, 1, 1},
    {1, 0, 0, 1},
    {1, 0, 0, 1}
  ] => "A",
  [
    {1, 1, 1, 1},
    {1, 0, 0, 0},
    {1, 1, 1, 0},
    {1, 0, 0, 0},
    {1, 0, 0, 0},
    {1, 1, 1, 1}
  ] => "E",
  [
    {1, 0, 0, 1},
    {1, 0, 0, 1},
    {1, 1, 1, 1},
    {1, 0, 0, 1},
    {1, 0, 0, 1},
    {1, 0, 0, 1}
  ] => "H",
  [
    {1, 1, 1, 0},
    {1, 0, 0, 1},
    {1, 0, 0, 1},
    {1, 1, 1, 0},
    {1, 0, 0, 0},
    {1, 0, 0, 0}
  ] => "P",
  [
    {1, 1, 1, 0},
    {1, 0, 0, 1},
    {1, 0, 0, 1},
    {1, 1, 1, 0},
    {1, 0, 1, 0},
    {1, 0, 0, 1}
  ] => "R",
  [
    {1, 1, 1, 1},
    {0, 0, 0, 1},
    {0, 0, 1, 0},
    {0, 1, 0, 0},
    {1, 0, 0, 0},
    {1, 1, 1, 1}
  ] => "Z"
}

:ok

Part 2 first try

folded_points =
  Enum.reduce(folds, points, fn {fold_axis, fold_value}, acc ->
    if fold_axis == "x" do
      Enum.map(acc, fn {x, y} ->
        if x > fold_value, do: {fold_value * 2 - x, y}, else: {x, y}
      end)
    else
      Enum.map(acc, fn {x, y} ->
        if y > fold_value, do: {x, fold_value * 2 - y}, else: {x, y}
      end)
    end
    |> Enum.uniq()
  end)

[x_max, y_max] = for xy <- 0..1, do: folded_points |> Enum.map(&elem(&1, xy)) |> Enum.max()

blank_paper =
  for x <- 0..x_max,
      y <- 0..y_max,
      into: %{} do
    {{x, y}, 0}
  end

dotted_paper =
  Enum.reduce(folded_points, blank_paper, fn point, acc -> Map.put(acc, point, 1) end)

dotted_paper
|> Map.to_list()
|> Enum.sort()
|> Enum.map(fn {_, val} -> val end)
|> Enum.chunk_every(y_max + 1)
|> Enum.chunk_every(5)
|> Enum.map(
  &(&1
    |> Enum.slice(0..3)
    |> Enum.zip()
    |> then(fn grid -> Map.get(letters, grid) end))
)
|> Enum.join()