challenges

my solutions to various "programming challenge" problems
git clone https://wehaveforgeathome.hates.computer/challenges.git
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011.pl (3070B)


      1 #!/usr/bin/perl
      2 
      3 use strict;
      4 use warnings;
      5 use List::Util qw(reduce);;
      6 
      7 my $input = <<'END';
      8 08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
      9 49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
     10 81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
     11 52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
     12 22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
     13 24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
     14 32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
     15 67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
     16 24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
     17 21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
     18 78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
     19 16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
     20 86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
     21 19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
     22 04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
     23 88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
     24 04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
     25 20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
     26 20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
     27 01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
     28 END
     29 
     30 my @nums = map(int, split(/\s+/s, $input));
     31 my $board = [];
     32 for (my $i = 0; $i < 20; $i++) {
     33   my $row = [];
     34   for (my $j = 0; $j < 20; $j++) {
     35     push(@{$row}, shift(@nums));
     36   }
     37   push(@{$board}, $row);
     38 }
     39 my $highest_product = 0;
     40 
     41 # horizontal "-"
     42 for (my $row = 0; $row < 20; $row++) {
     43   for (my $col = 0; $col < 16; $col++) {
     44     my @line = (
     45       $board->[$row][$col],
     46       $board->[$row][$col + 1],
     47       $board->[$row][$col + 2],
     48       $board->[$row][$col + 3]
     49     );
     50     my $product = reduce {$a * $b} @line;
     51     if ($highest_product < $product) {
     52       $highest_product = $product;
     53     }
     54   }
     55 }
     56 
     57 # vertical "|"
     58 for (my $row = 0; $row < 16; $row++) {
     59   for (my $col = 0; $col < 20; $col++) {
     60     my @line = (
     61       $board->[$row][$col],
     62       $board->[$row + 1][$col],
     63       $board->[$row + 2][$col],
     64       $board->[$row + 3][$col]
     65     );
     66     my $product = reduce {$a * $b} @line;
     67     if ($highest_product < $product) {
     68       $highest_product = $product;
     69     }
     70   }
     71 }
     72 
     73 # diagonal "\"
     74 for (my $row = 0; $row < 16; $row++) {
     75   for (my $col = 0; $col < 16; $col++) {
     76     my @line = (
     77       $board->[$row][$col],
     78       $board->[$row + 1][$col + 1],
     79       $board->[$row + 2][$col + 2],
     80       $board->[$row + 3][$col + 3]
     81     );
     82     my $product = reduce {$a * $b} @line;
     83     if ($highest_product < $product) {
     84       $highest_product = $product;
     85     }
     86   }
     87 }
     88 
     89 # diagonal "/"
     90 for (my $row = 3; $row < 20; $row++) {
     91   for (my $col = 0; $col < 16; $col++) {
     92     my @line = (
     93       $board->[$row][$col],
     94       $board->[$row - 1][$col + 1],
     95       $board->[$row - 2][$col + 2],
     96       $board->[$row - 3][$col + 3]
     97     );
     98     my $product = reduce {$a * $b} @line;
     99     if ($highest_product < $product) {
    100       $highest_product = $product;
    101     }
    102   }
    103 }
    104 
    105 print "$highest_product\n";