Day 3 - Advent of Code 2016
Mix.install([:kino, :benchee]):ok
Links
Prompt
--- Day 3: Squares With Three Sides ---
Now that you can think clearly, you move deeper into the labyrinth of hallways and office furniture that makes up this part of Easter Bunny HQ. This must be a graphic design department; the walls are covered in specifications for triangles.
Or are they?
The design document gives the side lengths of each triangle it describes, but... 5 10 25? Some of these aren't triangles. You can't help but mark the impossible ones.
In a valid triangle, the sum of any two sides must be larger than the remaining side. For example, the "triangle" given above is impossible, because 5 + 10 is not larger than 25.
In your puzzle input, how many of the listed triangles are possible?
To begin, get your puzzle input.
--- Part Two ---
Now that you've helpfully marked up their design documents, it occurs to you that triangles are specified in groups of three vertically. Each set of three numbers in a column specifies a triangle. Rows are unrelated.
For example, given the following specification, numbers with the same hundreds digit would be part of the same triangle:
101 301 501
102 302 502
103 303 503
201 401 601
202 402 602
203 403 603
In your puzzle input, and instead reading by columns, how many of the listed triangles are possible?
Although it hasn't changed, you can still get your puzzle input.
Input
input = Kino.Input.textarea("Please paste your input file:")input = input |> Kino.Input.read()" 330 143 338\n 769 547 83\n 930 625 317\n 669 866 147\n 15 881 210\n 662 15 70\n 273 277 707\n 50 592 770\n 280 313 407\n 642 487 372\n 94 619 295\n 734 243 141\n 220 141 515\n 198 824 745\n 210 787 964\n 213 627 601\n 918 4 447\n 805 630 802\n 711 237 987\n 938 552 388\n 643 405 779\n 803 747 525\n 917 832 631\n 899 292 843\n 81 206 445\n 141 874 465\n 177 974 54\n 520 725 814\n 271 958 554\n 779 579 264\n 358 18 257\n 978 77 270\n 984 88 131\n 475 702 940\n 183 756 160\n 383 941 820\n 806 142 646\n 793 275 804\n 53 272 368\n 942 821 785\n 863 830 902\n 219 52 199\n 473 479 351\n 860 522 361\n 890 240 216\n 94 756 407\n 310 189 468\n 234 909 178\n 889 667 756\n 429 485 730\n 825 405 30\n 943 806 253\n 98 455 365\n 998 454 290\n 971 576 223\n 64 429 273\n 945 779 63\n 352 960 59\n 672 948 577\n 782 43 567\n 460 315 719\n 825 604 183\n 453 442 788\n 694 632 334\n 569 619 317\n 337 49 17\n 878 468 660\n 393 598 717\n 550 827 159\n 540 362 346\n 66 713 380\n 491 477 44\n 411 114 320\n 554 96 250\n 306 67 196\n 769 553 333\n 762 436 382\n 278 322 153\n 894 603 334\n 539 441 844\n 486 162 927\n 197 9 218\n 94 221 804\n 250 220 913\n 557 626 486\n 562 705 630\n 968 922 285\n 518 36 468\n 18 608 83\n 512 611 530\n 534 37 65\n 621 136 90\n 239 113 139\n 371 640 956\n 629 54 959\n 531 620 338\n 682 499 810\n 798 170 968\n 187 640 645\n 660 535 332\n 663 530 314\n 64 26 65\n 55 285 488\n 620 288 52\n 642 474 450\n 455 9 962\n 51 760 489\n 426 760 833\n 304 783 772\n 498 765 695\n 635 53 126\n 44 430 774\n 979 943 838\n 962 892 64\n 494 709 614\n 7 695 120\n 503 114 606\n 362 340 689\n 509 367 389\n 673 410 664\n 773 262 558\n 897 958 245\n 140 773 483\n 965 468 584\n 546 209 668\n 856 381 184\n 274 237 762\n 888 677 906\n 871 516 405\n 102 529 912\n 285 724 885\n 352 501 53\n 774 139 245\n 380 309 594\n 813 185 765\n 530 645 965\n 958 618 120\n 851 202 957\n 737 476 131\n 595 546 108\n 716 113 66\n 327 215 318\n 397 343 390\n 351 143 103\n 138 91 31\n 108 224 919\n 230 276 896\n 426 975 177\n 327 975 918\n 238 365 764\n 328 799 775\n 590 906 967\n 578 460 338\n 507 619 647\n 711 617 867\n 933 478 734\n 820 760 721\n 199 711 824\n 983 214 228\n 382 150 648\n 415 782 242\n 615 754 445\n 693 689 590\n 382 784 482\n 997 181 322\n 682 241 172\n 587 302 252\n 184 135 254\n 574 104 549\n 88 738 796\n 486 715 861\n 62 491 815\n 463 434 569\n 519 622 310\n 199 443 782\n 572 657 85\n 763 517 844\n 750 175 835\n 228 269 710\n 611 316 551\n 883 546 296\n 169 693 18\n 992 743 316\n 263 529 529\n 705 570 4\n 918 706 527\n 609 285 971\n 260 533 112\n 711 486 904\n 820 40 472\n 997 301 129\n 257 288 343\n 635 439 375\n 560 381 417\n 773 105 145\n 58 963 267\n 976 742 424\n 994 441 384\n 389 770 514\n 782 463 335\n 919 727 276\n 780 794 372\n 326 180 590\n 918 946 257\n 889 842 181\n 507 61 464\n 762 835 443\n 827 607 982\n 174 875 544\n 934 885 589\n 32 343 757\n 987 826 257\n 981 782 844\n 446 291 397\n 443 800 421\n 165 668 539\n 410 373 487\n 422 803 881\n 546 998 953\n 291 607 160\n 919 894 62\n 842 718 117\n 110 816 582\n 470 836 596\n 575 687 35\n 37 835 374\n 90 954 354\n 101 141 407\n 174 398 499\n 173 737 964\n 4 365 950\n 946 616 634\n 906 904 619\n 40 789 16\n 788 769 76\n 737 867 88\n 565 812 31\n 508 380 201\n 34 935 339\n 500 862 326\n 431 181 475\n 403 346 585\n 88 530 708\n 731 137 781\n 715 563 272\n 817 659 932\n 396 368 360\n 162 683 376\n 278 620 39\n 525 910 371\n 688 524 149\n 488 998 279\n 286 392 523\n 325 144 406\n 79 532 419\n 540 460 465\n" <> ...
Solution
defmodule Day03 do
defdelegate parse(input), to: __MODULE__.Input
def part1(input) do
input
|> parse()
|> Enum.count(fn [a, b, c] ->
a + b > c and a + c > b and b + c > a
end)
end
def part2(input) do
input
|> parse()
|> Enum.chunk_every(3)
|> Enum.flat_map(fn triplet ->
triplet
|> Enum.zip()
|> Enum.map(&Tuple.to_list/1)
end)
|> part1()
end
defmodule Input do
def parse(input) when is_binary(input) do
input
|> String.split("\n")
|> parse()
end
def parse(input) when is_list(input) do
Stream.map(input, &parse_line/1)
end
def parse_line(line) when is_binary(line) do
line
|> String.split(" ", trim: true)
|> Enum.map(&String.to_integer/1)
end
def parse_line(line) when is_list(line), do: line
end
end{:module, Day03, <<70, 79, 82, 49, 0, 0, 10, ...>>,
{:module, Day03.Input, <<70, 79, 82, ...>>, {:parse_line, 1}}}
[[1, 2, 3], [4, 5, 6], [7, 8, 9]]
|> Enum.zip()
|> Enum.map(&Tuple.to_list/1)[[1, 4, 7], [2, 5, 8], [3, 6, 9]]
In your puzzle input, how many of the listed triangles are possible?
Your puzzle answer was 917.
Day03.part1(input)917
In your puzzle input, and instead reading by columns, how many of the listed triangles are possible?
Your puzzle answer was 1649.
Day03.part2(input)1649
Both parts of this puzzle are complete! They provide two gold stars: **
At this point, you should return to your Advent calendar and try another puzzle.
If you still want to see it, you can get your puzzle input.
